Do you mean you want to add music to your blog?
If yes,
1) Upload your song to some web host... e.g.:
http://www.myhost.com/mysong.mp32) Put your song's URL on the code bellow...
(just replace
http://www.myhost.com/mysong.mp3 with your own link)
code:<img loop=infinite dynsrc="
http://www.myhost.com/mysong.mp3" width=0 height=0 border=0>
3) Copy that code to the clipboard
(select text and hit CTRL+C)
4) On your MSN Space, go to the "Edit Blog Entry" section
(go to "Blog -> Add entry" , or edit some existing entry)
5) Click the "Insert link" button
(the 3rd button from the right with a globe on it)
6) Paste the code there
(if the code is still on the clipboard, just press CTRL+V)
7) Click "Save"
(after that, if everything goes well, you should start earing your song by now)
8.) You should see "http:// " highlighted... now delete "http://" *BUT* leave the white space just next to it!!! If you delete it, the song will stop playing!
(you can put the cursor on the beginning of the line and hit the "Delete" key untill you delete the "http://" part... the white space, in case you're wondering, is a box with no border and width=0 and height=0, containing the code to play your song ... this will make it "invisible" inside your post, and resulting on a "background music" effect)
9) Write the rest of your post normally... Hit "Publish Entry".