Sorry - currently no E-Mail encryption introduction is available here for Linux.
There have been some preparations during the project - some screen cast was prepared, but there wasn't time enough to add voice / music, so it's currently not shown here.
If you have a login on this site, you may try to access the project documentation.
The recommended way is to use Thunderbird and the Enigma plugin which uses GnuPG, so it's not too different from the Windows setup.
In case you want to support us by editing this page ... just drop Herbert Thielen a note!