First, welcome to the Forums! Always good to have new roboteers.

Second, can you tell us what kind of experience you have, if any, and how much you know about the robots in general.

There are many threads in this section asking exactly the same question... here is a excerpt of some part reconsiderations that were suggested to another newcomer just this week...

2x Botbitz TZ85A speed controllers
1x Orange RX R620 receiver (or equivalent)
Spektrum transmitter (again, or equivalent, I have a DX5e)
Pair of cordless drills/see if anyone's selling a set of GR01/2 gearmotors (nopw our
12v battery, I would say 3S LiPo but I'd probably advise newcomers against jumping straight into LiPo batteries because there's extra rules and regs on them all (and safety precautions). Probably a 12v NiMh or something would do the trick.

Add wheels and a chassis, you're good to go - wheels can be found on various places, or done yourself (Ellis - https://www.youtube.com/user/TeamExpat/ - has some great tutorials on this, as well as https://www.youtube.com/user/RobowarsNSW) and a chassis can be constructed out of wood, or HDPE with very basic tools.

Look in the Build Diary's section for hits tips and building techniques. We tend to suggest your first machine is just a push bot or an electric lifter to help you get the basics down of you have very little experience. You will learn the most by competing and going to events so build something, turn up, have fun, learn and then you can sit down and design a serious bot!

Good Luck!