[@Astarael42]

You simply use the little chain icon in the post box. 

[code][url][/url][/code]

Then add your url like so... (I'm using chapter 1 of a Librivox reading of Wuthering Heights)

[code][url=http://ia601707.us.archive.org/12/items/wutheringheights_1306_librivox/wutheringheights_01_bronte.mp3][/url] [/code]

And then add the text you want to display it as!

[code][url=http://ia601707.us.archive.org/12/items/wutheringheights_1306_librivox/wutheringheights_01_bronte.mp3]Wuthering Heights Chapter 1[/url][/code]

End result?

[url=http://ia601707.us.archive.org/12/items/wutheringheights_1306_librivox/wutheringheights_01_bronte.mp3]Wuthering Heights Chapter 1[/url]