Generate the private key
openssl genrsa -out domain.sihnon.net.key 1024
Generate the Certificate Signing Request
openssl req -new -key domain.sihnon.net.key -out domain.sihnon.net.csr
Send the CSR to cacert.org, and cat the result into domain.sihnon.net.pem.
Set up the server to use the .key and .pem files.