There are a few forces at work here. First you have force from your foot hitting the bottle of air or air pump. This would be considered applied force as your foot is applying the force to the air pump. You would also have a force from the air pushing on the rocket, which in turn pushes the rocket off of the launcher. This goes with newtons third law that for every action there is a reaction. As the air pushes in the rocket, the rocket pushes back on the air thus giving it lift. The last two forces that you have occuring are gravitaitonal force and air frictionl. These two forces are what slow the bottle and eventually what make it stop. Hope this helps.