Permalinks

I want to customize my permalinks, but when I do it of course, breaks all of the old links and I get the 404 page not found message.

When I read on the forums about this issue, it mentions using “Advanced Permalinks”, but I don’t understand how to do this, and I’m not savvy enough to write any codes in Editor. Can someone help?

http://www.tslseattle.org

http://wordpress.org/extend/plugins/advanced-permalinks/