Welcome to the fantastic, sometimes frustrating but most often glorious world of 3D printing David! :)
Your question is really very very broad, but here's my contribution to make your first steps a success. First of all: I don't have experience with the Robo R2, but judging from the specs available online, I would say that you got a machine that take care of most of the troubles beginners encounter when starting out (e.g.: levelling the bed) and has a few features that allow you to print more reliably/with better quality (heated bed, enclosure, possibility for a second extruder).
Give a hug to whoever made the gift to you! ;)
I like to think to 3D printing as a process that involves 4 phases (well, normally several iteration of them as prototyping is a thing):
- Designing (creating the mesh, i.e. the shape of the object you want to print)
- Slicing (creating GCODE, i.e. the file with the step-by-step instructions for moving your printer nozzle in space, extruding the plastic, controlling temperatures and cooling, etc...)
- Printing (the actual process of having your printer running that GCODE)
- Post-processing (finishing the piece, by for example removing support material, sanding, vapor-smoothing the surface, painting, etc...)
Technology in the 3D printing world is moving so fast that printed information tends to get outdated quickly, and the Internet is often the best source of information. So in the following bits I will mention the the source of information that I use[d] for myself, of which many are online rather than in print.
Broadly speaking, there are two kind of designs one can do: decorative or functional. Decorative designs are those in which the final object will essentially sit still on a shelf or be handled very gently (e.g.: a model of the Tour Eiffel, a miniature for RPG gaming), functional designs are those in which the final part will have to bear a load or perform some sort of mechanical work (e.g.: a drone, a shelf bracket, a pipe adapter...).
Both designs need to take into consideration the physical limitations of FDM printers such as the fact that the nozzle is round and with a fixed diameter, or the fact that molten plastic needs to rest onto something, thus the need for support.
Additionally, functional design requires an understanding of the physical properties of 3D MFD printed parts (hint: they are anisotropic, so their properties differs along their axis). If you are interested in functional designing a book that I can highly recommend is Functional Design for 3D Printing by Cliff Smyth. It is concise, accessible and full of information you'll be using from your very first design.
In terms of tools, for decorative, organic forms, you will probably want to use a program like Blender, that manipulate meshes directly, while for functional designs will probably turn to CAD software, like for examaple FreeCAD that operate on a "model" and let you export the finished part as a mesh at the very end.
Both Blender and FreeCAD are free software (like in: "free speech") but commercial versions do exist as well (most notably from Autodesk).
Blender is professional grade software with a very steep learning curve and I would suggest to take an structured online course like this one about it, rather than trying to learn it the DIY way.
FreeCAD belongs to a category of CAD programmes that operate on a well defined, well understood, set of principles (so it works similarly to OnShape and Fusion360 for example) and it is much easier to learn. In my experience CAD modelling is best learnt by understanding the very basic, and then just researching further information as you go, according to the needs of your project as CAD design is full of small specific operations that is useful to know only if you actually need them (e.g.: how to draw a screw thread, or to perform a loft). I started out with this series of video tutorials by the late Roland Frank (a celebrated contributor to the FreeCAD community), but there are tons of other tutorial should you choose to go with a commercial product.
Slicing is as much an art as it is science. While the actual work of generating the GCODE is automated and requires just the click of a button, there are a myriad of settings that are mutually interdependent in their effect. For example: filament temperature, movement speed, cooling fan, retraction and coasting all affect oozing, but each of them also affect other things (bridging, layer adhesion, curling, nominal overextrusion, etc...).
Also: settings differs for each filament material, each brand, and sometimes even different spools from the same material/brand. Moreover, you may wish to tune them depending to what you are printing (maybe you are printing a finely detailed miniature and want to go slower to reduce vibration, or maybe you are printing a torsion bar and want to increase the temperature for increasing layer adhesion, for example...).
IMO the best way to understand how settings affect your print is playing around with calibration towers (example) and torture tests (example).
Calibration towers work by printing the same thing on top of each other but changing at each repetition a specific setting (like filament temperature, or extrusion multiplier). You will then visually inspect the final piece and evaluate how the print quality changed relative to that parameter.
Torture tests work by putting in the same piece a number of features that are hard for the printer to print correctly (thin walls, bridges, overhangs, to name a few).
A specific model that is sort of gold standard as a basic test is the 3D benchy. The good thing about it is that it comes with a full website that also tell you how you can evaluate the print. However, the benchy - differently than torture tests - is not designed to let you discover the limits of your printer, it is more of a quality-control test. If you can print a 3D benchy, you should be good to go for printing "regular" objects.
Also, at least in the two most common free-as-in-freedom slicers (Cura and slic3r Prusa Edition) each setting comes with some explanatory text while hovering on it, that helps a lot understanding what that setting does).
How much you can affect the actual printing process depends from how "open source" is your printer, and if it uses standard components or not. Consumer-grade printers get often upgraded/modded to improve print quality or tweak them for a specific job/material. Typical upgrades are extruder upgrades, stepper motor upgrades, vibration dampeners, different sensors, etc...
Each printer is unique, but normally you can find abundant information wherever the community of owners of a specific model gathers.
I would also advise to subscribe to some good youtube channel about 3D printing like Tom's or Makers Muse or Joel's, and to visit sites like All3dp regularly. As I mentioned, 3D printing tech changes constantly, and it is good to keep tabs on new materials, new software, new components, etc...
This is entirely dependent from the material you used for the print, its size, and its intended use, but I wanted to mention this nonetheless as there are amazing things you can do with acetone on ABS, lot of elbow grease on PLA or the use of an airbrush... so you know 3D printing does not end with the print! ;)
Hope this helps you at least a bit. Again: welcome to the the 3D printing world! :)