Hmmm... So we have a novice here 
Its great putting up ur question here.
For making a robot (simple one) you least gotta have basic knowledge of Electronics n Mechanical physics.
There are numerous ways of making a Toy car (in this case robot). So i suggest u to go through a theory session first, like what are the various types of robot people generally make, what are there mechanisms , power-sources, controls...etc. This will give u the idea what u hav to make.
Well since u are new to all this i suggest u to read the posts in this forum, go through the technical sessions n try to figureout wat problems generally ppl hav making the bots. Once u hav idea what type of wheel-drive u hav to use, the type of motors u may need n power source... it will be easy to design ur own robot car.
Dont worry its not a big deal as it sounds.
Have patience, surf net, use youtube... N yes once u hav idea wats ur aim, comeback here n let us know.
In case u just want a simple design n not wanna learn from the beginning, ask us again.
All the Best!!
