How do I use 3 Servos?

Hello all! This is my first post. I'm having problems while trying to get a simple 3 servo robot working. What I'm trying to do is use pins 9-10 to run my 2 servos for the wheels and a 3rd pin to run a sweeping servo for a ping sensor. I dont know what pin to use to sweep the ping servo. can someone point me to an example of a set up like this maybe some code to use anything thanks.

The servo library distributed with the arduino only supports two servos. The library discussed in this thread can drive three (or more) servos: