You might want to consider vinyl siding instead of aluminum. For a first-time DIYer, it's easier to work with and more forgiving. It's OK to bend it and it's easy to cut. Plus, since you have a garage, it shouldn't cost that much.
If you go to Ashland-Davis WEB Site, select Installation in the PROFESSIONAL pull-down menu, you'll see a number of PDF instruction manuals. Download the 'simple' version. (It's labeled Installation guide.) Measure out your walls in square feet, and divide by 100. That will tell you how many squares you have. (1 square = 100 sq. ft.) Buy a little extra for waste and scrap. 20% extra (for mistakes and possible future repairs wouldn't be out of the ordinary for 1st-time DIYers.)
If you go back to Ashland-Davis' main WEB page again, and select Siding Fundamentals, then click 'Is this job for me?', and read the page and links there, you'll get a good feel if this is for you. Also listed in all that is what tools you'll need. (A hammer, a 9" triangle, snips, just to name a few.) For what you're doing, it's not that hard.
To answer your original question, I can't help you on aluminum. (I've never installed it.) Oh, some 'other thoughts' ... Aluminum dents easily, it 'chalks' over time, and you're limited in selection. My best to ya and hope this helps.
PS: After this afternoon, I won't be back until Monday morning. 'Other Follow-uppers' will be around ...