If you're talking about a clicking noise you hear inside the vehicle when you push the pedal, then you are probably hearing the sound of the solenoid that allows you to move the shift lever.
When you first get in the vehicle and start it up, in order to shift from park to drive you need to push on the brake pedal. This activates a solenoid to electronically release the neutral safety switch. This is a normal noise.
If you are hearing something else, let me know when it's happening and I'll try to help you.
〉 Answered on Jun 18th, 2008 by Lori Johnson, Owner and Instructor at Ladies Start Your Engines