I am not that familiar with the Galaxy Tab 2, but you will need to find where in the file structure the external card mounts. Then move the files to or from the external storage and the /sdcard/ directory.
/sdcard/ is the internal storage directory. I believe Samsung mounts the external storage in a subfolder like /sdcard/external/ but I could be wrong.
You will need a file manager, not sure if one comes installed. My favorite is ES File Explorer.