How do you say check in in Spanish?

I recently moved to Spain with my family and have been trying to learn some basic phrases. One thing that has come up repeatedly is how to ask for a room at a hotel or hostel. I've heard that in Spanish, this is often referred to as 'check-in' but I want to make sure I get it right. Can anyone explain to me how to say "check in" and any other relevant phrases I should know when arriving at my destination?