radio and wiring

i decided i wanted to put a cd player in my car and so i took the stock radio out and then i thought that maybe i could cut the wires and then wire them to the wires from the new cd player i bought but i couldnt so i put the wires back into the harness that was on it and then put the radio back into the dash but now i cant unlock my doors from the inside or using my keyless entry either also the interior lights dont work now someone told me that its just a security thing and that i just have to find out the security code but i dont know how to get it and also when i turn the car on the lights in the radio and around the radio work so that means that it is hooking up and has power right? well that is about it but i really need help asap because i need to figure this out thanx