Importing songs from Windows Media to Itunes?

I just got a new Ipod and I installed iTunes for it. When I installed it, it asked me if I wanted to import all the music on my computer, which I agreed to because I have a lot of songs on my Windows Media Player that I downloaded from Frostwire. But when I did that, it imported 2 or more copies of each song, (presumably one copy from Windows Media and one from the frostwire database), plus a lot of songs that I didn't want, so I decided to delete everything and just import the playlist I wanted from Windows Media Player. However, I've clicked the "add folder to library" and it says I have no items matching my search, I tried adding file to library and clicking the playlist I wanted but whenever I do that iTunes doesn't do anything, it's like I never clicked on it. Does anyone know how I can import my music?