How to copy music from laptop to iPhone 5

By trial and error I copied 3 of my music folders from Windows 7 laptop to iTunes and again somehow managed to bring one folder of about 200 songs to the iphone5. But even after 3 to 4 hours of effort, I could not bring the other playlists to the phone. I am not even aware where the songs are in iphone. But when I click the playlist names I can see all the songs listed in iTunes. How can I  understand the process of transferring/copying music stored in the laptop to iTunes and from there to the phone ? Will someone explain the process to a Dummy?