Car Forum World

ok so I got a 04 chevy impala ls a couple months ago and today as I got home from school I locked my car then for some not known reason I unlocked it, locked it again then pressed the trunk button twice to get my backpack and out of no where my car starts. I had to get in my car and press my brake to stop it. I tried numerious time to repeat this procedure but it isn't working. Can anybody tell me how to remote start my car? All I have is a unlock, lock, trunk and alarm buttons.