The pill

Okay, so I'm 19.. Been sexually active about 2 years and have only used condoms as a contraception. I recently got pregnant.. Unplanned. So I've been going through the termination this last week. The doctor gave me a script for the pill, but I haven't taken it yet. Could someone please explain the whole process to me? And if you started taking it after a termination, how you did it? I've got the combined pill if that helps? Thankyou in advance :)