Rip (or "copy") the compact disc onto your computer. Insert the CD into your computer and open a CD-copying program such as iTunes, Windows Media Player or Winamp. To copy the songs into your software, click the "Rip," "Copy" or "Import" option appearing on your program window.
Select a song you want to use and import into a digital audio editing program. This may include a professional mixing program like Cubase or Pro Tools, a simpler program such as GarageBand or MAGIX Music Maker, or a free program like QTractor or Audacity. To easily import a song, drag the song file from your burning software onto your desktop, open your audio editing software and drag the song file directly onto the software window. That process automatically saves the file onto a blank track, or recording space.
Choose a portion of the song file that you want to use for your backing track. You may want to sample the chorus, the introduction melody or a particular instrumental riff. To isolate a portion of a song, drag your timeline indicator (the vertical line that spans along the file region as the song plays) to the "Start" point of the clip you want to save. From there, locate the "Cut" or "Split" option, sometimes appearing under your menu bar, and sometimes appearing directly on your window. It may appear as a button featuring a pair of scissors. After you cut the "Start" point, place your indicator at the "End" point and make a second cut, isolating your desired section from the rest of the song.
Delete the sections appearing before and after your two region cuts. For example, if your first cut appears at the "01:30" mark, click the region that appears before "01:30" and click "Delete" on your keyboard. Then click the region that appears after your second cut and click "Delete" again. Now only your desired section is visible. Drag this section to the beginning of your time line, at the "0:00" mark.
Loop your saved region. "Looping" simply refers to repeating your sample as many times as needed. Click the right edge of your region and drag it to the right along the timeline. Continue to drag the region until it repeats as many times as needed.
Save your project by clicking "File" on the menu bar and selecting "Save." You can then export the song as an audio file by clicking the "Export," "Bounce" or "Save as MP3" option, usually found under the "File" or "Sharing" menu on the menu bar.