How can I cut down a song in audacity?

I wanna take the song Baby and merge it with Rick Astley. How do I cut the song on audacity?How can I cut down a song in audacity?
Here are some videos that should help you along your way there are so many good videos to choose from the first one is a good one at the 2:50 mark is where he shows you what you want to know

http://www.youtube.com/watch?v=dbqJVC6kQ鈥?/a>

http://www.youtube.com/results?search_qu鈥?/a>

http://www.youtube.com/results?search_qu鈥?/a>

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