rebel8: As a kid, I put in many hours working in the garden, my father was a big believer in gardening. Not only did we have our own produce, but it kept all us kids busy working (idle hands are the devil, ya know), and it was good practice for Armageddon when food wouldn't be in the grocery stores. I haven't touched a garden since. But to answer your question, composting isn't that hard. Nature does most of the work. Our bin was a converted hog pen, concrete floor with wooden plank sides, about 10' x 10', and maybe 5' tall? I dunno, might have been less than 5', I was small then, so everything seemed bigger-I just remember as a kid that I had to struggle to lift the slops bucket high enough to dump it in over the side.
Anyway, the biggest chore is seperating your trash...food scraps go in the compost; banana peels, potato skins if you peel them, anything and everything organic. (except for bones and such, which went to the cats), paper and plastic go in the regular trash. I remember getting yelled at once for throwing eggshells away in the wrong trash, and being told that eggshells were especially good, cause they had minerals and stuff in them, toss 'em right in. Also, whenever we mowed the grass, all the clippings went in the pile, too.
Don't worry about freezing temps, you definitely don't want compost in your garage, lol. Like I said before, mother nature does most of the work, you want the compost heap outside where it can decompose, it would be too sheltered from rain and the elements in your garage, and stinky besides. In fact, you want it as far from the house as possible, within reason. Which means, depending on the size of your property, it can be a hike to go dump stuff in it. (And when you're a kid, a full-tilt sprint returning to the pool of light from the back porch when you had to do the chore after dark, cause you just read Something Wicked This Way Comes or whatever other scary thing, lol.)