To help get you started with CAD Drawings, you can go to our FRC Drawing tutorial
here. Review Unit 6 Manufacturing and Parts and Unit 8 Teamwork tools.
In SolidWorks, you usually begin with the 3D model of a part, from there you make the part drawing. You combine parts to create an assembly, from there you create an assembly drawing. Unit 8 Teamwork talks about the very important "pack and go" feature to keep your part, assembly, and drawing files all together. This is very important.
One of the other things that is helpful is to create an additional column in your drawing Bill of Material that uses the parameter "Cost". When "Cost" is set for each part or assembly as a parameter individually, that parameter is shared by the drawing. You can sum up the Cost in the Drawing Bill of Materials to get Total Cost.
Also with Assembly Visualization you can sort by Cost to determine which parts cost the most. You can also use the same process to sort by Mass, to see which components are the heaviest.
Drawings and CAD models are not required for FIRST, but they also help document what you did for next year's team and to present a professional porfolio of your robot design process. Be certain to create a good title block with the correct units, school name, title, and revision. Don't get sloppy here.
I also believe drawings, if done according to an engineering standard, are valuable to the person on your team that has created them for the ever important job interview. One of the most popular SolidWorks certification exams this year is our SolidWorks Advanced Drawing Tools. Our commerical customers create drawings.
Good luck in the competition. Marie