You need to be registered and logged in to the Forums to post a song or playlist.
Upload song from the Song view:
Tap/Click the Share button -> Export Chord Chart
Apple Share button
Android Share button
Tap/Click Export Chord chart, then the Forums option. (It will automatically copy the song to your clipboard and open the Forums.)
Tap/Click on Log in and enter your username and password.
Tap/Click into the relevant forum area, then tap/click on New Thread to create a new one or reply to an existing thread.
Add a title, then tap and hold (or click) in the post's Message window then paste the song.
(Windows-Amazon users, right-click does not work for the option to paste, use the Windows key command, Ctrl-V)
Then tap/click on Submit to upload the song.
A playlist can be shared or posted to the Forums as well with the above steps.