Stockinette stictch does have a tendency to roll up.I don't know what to suggest.

Welcome to the wonderful world of yarns and needles! You will have a great time, I guarantee it.

Knitting a hat in the round is easy - no purling, a plus for those who dislike that stitch. However, without any ribbing/seed stitch/garter stitch to start the hat and help hold it on the lucky recipient's head, you will have a 'rolled brim' hat instead. They are fashionable and fun, but may not be what you wanted. Just start your hat with a few rounds of ribbing - k1, p1 (stitch count should be a multiple of 2) or k2, p2 (multiple of 4)are good ones. Or you can do some seed stitch, or a few rows of garter stitch, which done in the round would be k one round, p the next. Garter stitch and seed stitch are not as 'gripping' as ribbing, but will keep your fabric from rolling.

When you get to the decrease part of the hat, you will need double-point needles, as your stitch count will decrease and not stretch the full length of your circular needle.

Good luck with your project! And come back if you have other questions; someone will help.

Does the pattern picture show it with a rolled brim?

You may not need dpn,s you can magic loop when you get to the top

vickey