Thank you for using OnSong!  You will need to do the following:

1. View the set you want to export to Dropbox

2. Select the Share Menu

3. Select Export

4. Select the Wrench icon

5. As Single file selected

6. Done

7. Select the folder icon

8. Select Dropbox

9. Select the folder you want to export to in Dropbox

10. Tap on Choose

11. Select OnSong Archive

12. Export.

Please let me know if you have any further questions or concerns.