how to make a simple 4 wheeled robot

[soumen nayak]

hi i'm a beginner actually i want to know how would i design a simple 4 wheeled robot which can move on a rough terrain and can pick and throw a ball of 40mm diameter 

[waltr]

One way is to buy an RC truck and hack it for autonomous control. This gives you a chassis with wheels, motors and suspension.
Look around on robot web sites for info from people who have done this.