Hi Jason,
Let's address a pattern first. Please click this link. There are more than a dozen pumpkin hat pattern to choose from. Each pattern will state the recommended yarn and needle size.
http://www.ravelry.com/patterns/sear...ptioned_thumbs
If you are prompted to "join", please do so. It's free, and sign up is simple.
After you've chosen a design, then we can help you with the HOW TO aspects!
Welcome to our Knitting Help fam!