Emergency Contraceptive Advice

Hey guys! So my partner and I recently had unprotected sex (it wasn't planned and just happened) for the first time and I've been really nervous about it. Normally we're careful and take our necessary precautions but this time it just slipped our minds. I've never had to use Emergency Contraceptive before and would like to know how it works, what brands are most recommended and such. If anyone could provide me with some advice, I would greatly appreciate it.