We would like to add a one bedroom apartment above our 32x32 garage. I have a design that I have done on a Home suite program. Would like to know what needs to be done to make it happen.

#1 See if it's even permited in your area.
#2 Your going to need permits.
#3, You going to have to add a point of egress. Someplaces a window above a certin size will work, others require a set of stairs on the outside of the building.
Is there trusses of open rafters?
What size joist, and rafters were used?
What's there spacing?
Is there enough power avalible already in the garage?

And most important: Assess your own skills. This is a huge project the must be built to meet code requirements. If you do not know how to do this up front then your first step will be to find a good contractor to make this happen. Once you find a contractor to talk to, they can answer all your questions about how to make this happen.

you are also going to have to seal the garage fume-tight so anybody in the apartment won't be gassed by exhaust.

since garages are typically not weatherproofed, getting water/sewage to the apartment is a challenge, particularly since there won't be lines run to the garage. this means some hefty floor or slab chopping in the house. getting the right slope to the drain stack is also going to be challenging. and an "apartment" without a bathroom is not likely to pass muster with the city inspectors.

lots of real good reasons to pay a competent local contractor to assess the situation. just because you can draw something on a computer doesn't mean it can be done correctly and to code. there are ways to get around lots of issues. they add cost and complexity.