I do hope that your consulting the code enforcement department first and getting their input.
They will supply you with "standards" that they will want in place so they will not "red tag" you later on in your construction.
many people do not get permits on things like this and when a code person drives by and sees this "without a permit" you could be ordered to tear it down or at least tear a portion of it down to make sure your framing is by code.
Go to hometime.com for some plans or books on how to build a garage. Others will have other sites for plans also.
This will be fun for you. Also, take great pains in planning for now and for future in you building. Ie, electrical outlets, and insulation and of course drainage. Is rebar in your cement foundation?