Advice on insulating garage vents

Hi I was wondering if I could get any advice on how to insulate or seal garage vents. I don't park my car in the garage and I'm turning it into my man cave since it's the only room in the house that my wife will let me decorate lol. There is only 2 vents, one in the top and the other at the bottom. During the summer it gets really hot and in the winter really cold. I was thinking to insulate or seal these vents to keep my garage insulated as I will insulate the garage door as well. I was also thinking of installing a portable AC unit and have the exhaust go out of the bottom vent. Please help a brother out.