Gear design is a rather complicated topic as the tooth profile is highly important to a good gear. There are add on applications such as GearTrax from Camnetics (http://www.camnetics.com/) that will design the correct tooth profile based on your material, speed, and load inputs. If you want to do this by hand, perform a search on the internet for gear tooth design.
Thanks for the info. My academic license does not come with the Gear Designer add-on. This is the reason why I wanted to create a gear from scracth. I found this video on youtube https://www.youtube.com/watch?v=NQhaw5tfqk0 very helpful.
The technique will be the same regardless of CAD sytem. What he's doing is sketching the process of "unwinding a string" from around a circle to generate the curve. There are some other videos for generating the curve but this one seemed the most direct.