itunes

Hey, this is my first time to the site and I really just wanted some input on a problem I'm having with my itunes downloads. I'm trying to download Breaking Bad season 3 from itunes but my downloads keep stopping and a message says I'm out of disc space. I checked my memory and I have plenty left on my hard drive where is the memory low? Forgive me for sounding inane but I don't know a heck of a lot about how computers run and all I want is to free up space wherever it is low so I can watch this show!
Thank you in advance!

If you open up Finder, what does it say at the bottom of the window in terms of what's available? I just checked the iTMS and with 13 episodes at about 47 minutes each, that's going to take up a decent amount of space.