no worries - we all had to feel like we were asking silly questions at one point or another about computers.
If you start getting more USB devices than ports on your computer (easy to do if it's more than 3 or 4 years old), then go to Target or Wal-Mart and pick up a thing called a "USB Hub" it's sort of like a power strip for USB devices.
It only takes up one slot, but you can plug 4 or more devices into it (depending on how much you want to spend). I've seen them as cheap as $10, but I bet if I made an effort to look, I could find one for less.