step 1: buy solar panel , dc moto 3v and wheel
you can buy them on the internet , you seach on google " mini solar panels " and " dc motor 3v and wheel "
(very much and cheap ), solar panels 2$, motor 3v and wheel 4$
step 2: make electronic circuit
you can download guide document and layout PCB at here :
everyone watch " how to make mini solar car " at here