The cruise control is on the blinker lever on the left hand side of the steering wheel. First, as stated above, you move the switch the "On" position, as shown here:
Then, when you are at the speed that you wish to maintain, press and hold the "Set" button on the end of the lever for about 3-5 seconds, then just remove your foot from the gas pedal:
If you'll notice on the first picture of the on/off switch, you'll see where it says "R/A". That means "Resume" and "Accelerate". If you have to slow down for any reason, just slide the button over to "R/A" and let go, and it will resume your cruise control to the same speed it was before.
If you're cruising on cruise control, and wish to go bump up the cruise speed, just slide it over to "R/A" and hold it, until you get to your desired speed, then let off. It then will cruise along at the faster speed.
Hope that helps ya!