I have a 350Watts amp, and a 700watts sub, will it work?

they will work together. You need to find out the wattage ratings from the amp and the sup. Usually amps are rated at continuous watts while speakers are rated at max watts. If the sub can handle 700 watts max then it can usually handle half of that continuous which is good because it would be right in line with the amp. To hook an amp up to the radio in the car you Need a Power Wire that goes to the battery and remote wire that plugs into the wiring harness of the radio that goes to the amp and ground wire that you connect to the amp on one side and screw down onto any metal part of the car and a set of rca cables that go from the back of the radio to the amp. Then the rest would just be some speaker wire.