Question about adding files to iTunes library

Hello, a firstime iTunes user. Never liked iTunes on windows, used wmp and winamp. I also wasnt a fan of libraries, as I download music everyday and all I do would do to play is highlight my whole music folder and press play.

Now that I converted, I'm liking itunes and the whole library thing. Just a few questions.

All my music is stored in users>music. I download music into my downloads folder. Obviously not from iTunes, if I dont think I'd be asking this. But how do I get the new music, which I'm going to move into my users>music folder, to my iTunes library? Sometimes I download up to 10 songs at a time, a few times daily. Whats the best way to do this, I dont want to add songs to my users>music folder without being able to listen to it in itunes under my library. If that happens, which it already did, I will forget which song it was I downloaded and it will already be in my users>music folder.

Anyway sorry for babbling, hope I made sense. Thanks!