Tina,
I will repeat what the others have said...you are *not* stupid!!!
College has a way of showing us just how much we don't know...I actually had a professor who said that the only way he could find out how much we knew was to keep pushing until he got to something we didn't know. But that can be awfully hard for those of us who see anything short of perfection as a failure. But you are not expected to be perfect.
So take a breath, and just do what you can. And I have faith that you will do great.
{{{{{{{{{{{Tina}}}}}}}}}}}
Jo