Help with scrollpane component

I built a mp3 player (by a tutorial) that reads the data from xml file
when I add a new line of a new track to the xml file, a new button (with the track name) appears in the flash file below the previous button
the button is not on stage but it has linkage
the problem is that if I add lots of tracks the buttons will cross the screen
I want to put all the buttons in a scroll pane but I don’t know how
in the first pic you see the code for the movie clip that called track_list which is the grey rectangle
in the second pic you see the code in the button that right now is not on stage
and in the third pic you see how it looks like after I published
currently I have 5 tracks so the buttons don’t cross th screen
I hope you can help me
thanks!