You have to upload the mp3s (or wav) somewhere external. In the newest Version of Pocket Platformer, you can enter the URL to the Music directly in the editor. To change the SFX you have to edit the html code. This is simpler as it sounds: Open the HTML File (your game) with a text editor. Search for "google" in the code. You will have 7 hits: The first one is the font, the other six are URLs the the sound files for Jump (long and short), Dash, Hit, Win, Select. replace the google URL with the URL of your sound files. Don´t delete the " before and after the URL ;)