Import your song by dragging the audio file into the main editing interface. You may also go to "Import" under the "File" menu and select the song file.
Preview by playing the audio file and watching the cursor as it moves across the song. Find the point where you want to cut the song and place the cursor there. Use the zoom tool that looks like a magnifying glass to zoom in on the section you have selected.
Highlight the area before and after the cursor by clicking and dragging your mouse across the potential cut point. Press "Play" to preview the selected section and move the selection point if necessary. Everything after the cursor will be cut.
Cut the song by dragging from the cut point to the end of the file. Open the "Edit" menu and select the "Cut" option. This will cut the audio that you have selected.