Donating bone marrow? How bad is it?

Heey okay so there was an article in the newspaper about a woman who needed a bone marrow, & both me and my mom (I'm 14) are going to get tested to see if we're compatible for her. If I am, I want to donate, if I'm not, I would still like to be on the list for anyone who needs bone marrow. I am being put to sleep for it, does it hurt when I wake up? What else should I know about donating bone marrow?