opening or browsing for mp3 files in windows phone 7

im trying to cre开发者_如何学Goate a mp3 player for windows phone 7...how do i create a open file dialog or something that will allow me to access my files on the phone so that i can play them with my app"???

EG:

say i have a folder in my sd card...how do i browse to that folder so that i can imports the songs from that folder into a playlist in my app...

There are no standard open file dialogs for WP7. (some choosers excepted.)

If you want to do this you'll have to create the dialog yourself. You can get the details of the songs saved into the Music&Video hub via the MediaLibrary object. (Add a reference to Microsoft.Xna.Framework.dll to use this from Silverlight.)
You'll then have access to lists (collections) of Albums, artists, playlists, songs, etc.

If you want to play tracks you've save in IsolatedStorage you can access these directly yourself.