How to launch a manual car at the track?

So when i move up to the line at the track to race and stop, My Clutch is in, 1st gear is in, while tapping the gas to the right rev. Guessing it to about 2,200 / 3,000 rpm. But while in 1st/clutch in/and reving i see my car slowly starting to move forward. Does anyone know how do i launch it without it slowly creeping before going? Do i need to step on the brake and clutch at the same time? Please help (O:

I own a,
2008 Ford Mustang GT with a Roush supercharger and upgraded pulley.

Added (1)..

If your car keeps creeping forward with the clutch pedal pressed, this shows the clutch to be dragging, needing adjustment (or you need to press the pedal down further) so it releases drive completely between the engine and transmission. The dragging condition needs to be fixed because it will wear the clutch faster than usual and damage the transmission every time you change gear. Until then, you can hold the car stopped at the line using the hand-operated parking/emergency brake (releasing it as you lift your foot off the clutch pedal to go).

Keep in place with the hand-operated Handbrake or Emergency Brake, as you Americans call it.