First you need some keys. Import or create them via the option menus in "My Keys".
It is recommended that you install OI File Manager to be able to use the browse button for file selection in OpenPGP Keychain.
Please report it in the issue tracker of OpenPGP Keychain.
If you want to help us developing OpenPGP Keychain by contributing code follow our small guide on Github.
Help translating OpenPGP Keychain! Everybody can participate at OpenPGP Keychain on Transifex.