What kind of robot would you like to make?
I suggest the most simple, its called a 'Photovore.' All beginners start with this robot. If you dont know the basics, its a good robot to start with.
All you need is 2 wheels, 2 motors, a battery and a few wires, and a supercheap sensor called a 'photoresistor' which you can probably get from radioshack.
Browse the web for 'how to make a photovore robot.'
This should help too:http://www.societyofrobots.com/algorithms_photoresistor.shtmlhttp://www.societyofrobots.com/schematics_photoresistor.shtml
Also note, you do not need a microcontroller or any complicated circuit or electronics to build this robot.
If this does not help or you have more questions feel free to post em.