So I'm new to CADing... help a bro out!

[Sumdude]

Hello! So I've used AutoCAD a long time ago (couple of years ago or so, non-FRC related), but do you all have any idea how/where I can get started on CADing (specifically for FRC)? My friends recommended I use AutoDesk Inventor, but I honestly have never used that software before. Is there a library of CADs (like motors, channel metal, etc) I can use to import to create an FRC bot of some sorts? I've had only a basic understanding of making only one part in a CAD. So I have no idea how to assemble a robot out of multiple parts. Dx (Also, the art of CADing is kinda dead in my team, an older teammate that just graduated told me it is VERY important, and with it the building process goes by pretty fast).
Note: I have AutoDesk Inventor 2013 downloaded on my computer atm.
Any help is greatly appreciated! (Sorry if this post seems pretty stupid... I just don't know what to do) And again, Thank you!