If you dont even know where to recharge your A/C on your car I wouldnt even touch it. Filling it will damage the compressor or the fixed orifice tube, and if the refirgerent is low enough for the low press cycling sawitch to not allow operation of the compreessor, you have a leak and now air in the system, which when mixed with pag oil turns to acid and will eat you A/C system from the inside out. Besides if you are using the little refill cans, and dont do it right they can explode from the high side pressures. Find the leak fix it, replace the suction accum ulator, pull deep vaccuum, and fill with the required amount of refrigerent. Besides all that if you are not EPA 609 certified you are breaking FEDERAL laws just touching the stuff. Take it in to a shop and fix it right.