Welcome to the Forum!
If you are pretty new, my advice is to build a pretty simple 4 motor drive bot. Simplest chassis is to direct drive 4" wheels with 200 rpm (green) motors. This will be very simple, and a decent speed to start out with. It will also be super easy to program. Some topics about designing good drives have been posted by @Xenon27.
You should also check out these:
MENTORBUILT - A Robot Made in 12 Total Hours For Your Enjoyment
Harvard-Westlake Robotics: BLZ-i Reveal