Kremlin Decrypt allows you to decrypt the files you have encrypted. To use it, just double-click on the encrypted .kgb file. You should then enter your passphrase. It will appear obscured with stars (optionally disabled) to prevent other people from reading it off your screen.
By default, Kremlin decrypts all files in the .kgb archive. If you would like to choose which files to decrypt, uncheck the Decrypt All button and choose which files you would like to decrypt.