Point your gemini client to gemini://tilde.green
Just create your content and make sure it's within a public_gemini
directory in your $HOME dir.
If the urls do not work make sure that the permissions of your homedir are at least 711 and the permissions of the files are 644
CGI runs as the user under which's $HOME directory it is on. Just make
a program executable and it'll run when queried.
A very simple CGI script is test.sh:
#!/bin/sh
echo "20 test/gemini\r"
echo "this is a cgi script"
If you put that into your public_gemini, you can access it with
gemini://tilde.green/~username/test.sh
A gemini forum using bubble is at
gemini://forum.tilde.green/