A simple way to add tunes to any post (not the forum though)

First login, and go to create content, choose blog entry.

Make sure 'full HTML' is selected in the input formats, then type

[tune:http://linkToAmp3]

This will then be converted to something like this

If your tunes are not on the web already somewhere, then you can upload them to n23 as an attachment to your blog, then change the url to the link generted once you upload. Have fun.