Question about discussion board...

I've missed quite a few discussion board questions because I wasn't aware that I was supposed to be doing them...does anyone know if I can make them up? If so, where do I? How many do I need to do? Is there an article or something where I can read up on this? Thank you guys...I appreciate the help in advance. If you want to email me, it is K_riley15@hotmail.com
Thank you!
-Kirstie