If it is 5600 you just press the soft key to the left and select "media in miniSD and select the song you want to play...
Or hard way...
Press Menu/Ok located in the Center.
Go to tools/Extras
From Tools/Extras go to MiniSD
From MiniSD go to miniSD folders
Then go and select Media.
From there you can just select the song from your minisd you want to play and the phone will play it..
Hope this helps