After you've installed package PACKAGENAME, you can use the following command
to find the binaries (executables) it contains dpkg -L PACKAGENAME|grep /bin/
Those might be GUI apps or not. If you omit the grep part (|grep /bin/),
you'll see all files in the package. Looks like that python gpg package
doesn't contain binaries but comes with a README. Point your favorite text
editor to it, or try pointing the less command there.
Usually commands (executables) come with a manual page which you can access
withman COMMAND
(replace PACKAGENAME and COMMAND with actual names)
