Sign up for a free account at Esnips. It has a number of AuditionSEA tracks available free for download. You'll need to activate your account email.
Enter "AuditioSEA" in the search box at the top of the screen, select "Audio" from the drop-down menu and press enter. You'll be presented with a list of AuditionSEA songs.
Click on the song you want to edit then select "Download" below the media player on the song's landing page. An MP3 of your chosen track will start to download.
Save the MP3 to your hard disk once it has downloaded.
Open your audio editor and start a new project. The method for doing so will differ depending on the program you're using.
Create an audio track in your editor's sequencer and import the MP3 of the AuditionSEA track you downloaded.
Use your program's cut utility to edit the track. You can shorten the song or remix it by deleting sections or moving them with your program's item tool.