StyleForum just opened a "menswear primer" section on their website. The content is very, very good, and it covers many of the basic questions that men often ask when they first become interested in this subject. Note that in each article, there are really good links that will help direct you to threads and/ or articles that will discuss various topics in great detail. I’m not saying that, by the way, because whoever wrote these primers happened to link Put This On a bunch of times. They are legitimately really good links in there.
Incidentally, while I didn’t write any of the primers, I do write for their blog. You can read what I’ve written so far here.