How to transfer mp3 tracks into iTunes:
Download the file you want to save to your computer.
Note: When downloading files from the internet, they usually have obscure names and download in obscure folders. Make sure it is saved in a folder where you will remember it is with an easily recognizable name.
Once iTunes is open on your screen hit Ctrl+O. A box will appear on your screen where you can access all of the files on your computer.
Click the file you want and hit open.
Note: You can only add one file at a time, not a whole folder.
You may have to convert the file, but it will not affect the quality of the track.
AND THAT’S IT!