does anyone know how to sign with PGP key?

[dazzlingdazzler]

1 - Write a message in a text editor.
2 - Copy the message.
3 - Click on the clipboard on the right top of screen.
4 - Click in "Sign/Encrypt clipboard with public keys.
5 - On bottom of "choose keys" window in "sign message as" select your key.
6 - Hit ok and let us know the result.

I have done all this however I dont get a result. Nothing pops up??