In order to save a file to the SD card you must have permissions to write to the card. You need to add the following to your AndroidManifest.xml:
Next you open a file stream, write to it, and close it wherever you want to do that in code:
Note: you with get a FileNotFoundException if you try to open/create a file on the SD card when it is mounted on your computer. You must unmount it first before you can access it in your application.