How Do I Enable GnuPG in Sylpheed?

[rian]

Using FatDog500 on a 4GB mem stick. Sylpheed 3.0.2 was pre-installed. I installed GnuPG and GPGMe, both of which Sylpheed says it needs to encrypt mail. Still no options appear for encr in the program. Then I found this on the Sylpheed site:

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GnuPG: [...] To enable this feature, you need to install GnuPG and GPGME (interface library to GnuPG). Enable this option with the --enable-gpgme configure switch.
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Can someone tell me WHERE I "enable this option with the --enable-gpgme" switch? I am a total newbie to Linux. I opened a terminal window but it says "command not found." TIA!

(PS The only reason I'm not using Thunderbird and Enigma for encryption is b/c Enigma won't work in FatDog, though it works in Lucid Puppy.)