Pem encoded key

Hi, now there’s another issue with the PEM-encoded key. When I try to link server start9 to the VPS and stack here, it says an SSL certificate is required. You can have StartTunnel generate a certificate signed by its own Root CA, or provide your own certificate (and key).
SSL Certificate: Provide
Please paste in your PEM encoded private key: I am totaly new to all this and I want to learning.Thanks.