How Can I Make An Object Move Randomly?

Let’s say i want to make a sphere moving randomly but only inside specific axis range (like for x position should be between 4 and -4), how to do that?

getting that random number is like this:

x=Random.Range(-4, 4);

http://unity3d.com/support/documentation/ScriptReference/Random.Range.html

but if you want sphere to move from 4 to -4 in ping pong motion use this:

transform.position = Vector3(Mathf.PingPong(Time.time, 8)-4, transform.position.y, transform.position.z);

LOL whatever when u want to know smething it doesnt matter how may times iy has been asked.
BTW I gotta good solution by myself.
to move an object randomly into a limited space:

transform.position = Vector3(Mathf.PingPong(Time.time3,9.9)-4.9,Mathf.PingPong(Time.time3,7.1)-3.6,0);

just one line & u’ll get an object MOVE INTO A limited space like a ping-pong.