First, you have to figure out if you have clearcoat or not, hard to tell from your photo. You can tell if it has milky spotches with various degrees of oxidation showing through. If you do, the you need to strip that off first. There are several threads that discuss this process, find them by doing a search using the keywords "stripping clearcoat"...about ten threads will appear.
Then, spend some time on the Perfect Polish site
to learn about the polishing itself. There are also 15+ threads regarding this topic here as well...search using "polishing aluminum" as a starting point. Although, personally I feel the Perfect Polish site is great...a whole website dedicated to the subject, supplies & equipment in one place.
We are currently in the middle of this whole process...we have stripped the clearcoat and are awaiting warmer weather to start the polishing...good luck!