Hi guys, I noticed recently that if I use https instead of http before my domain somebody else's website shows up, it's a loan company. All the page links on this website show as my domain but with https in front. I certainly don't want nothing to do with this website.

That's technically not possible. Your ownership of your domain is not linked to the protocol that is used for access. It's irrelevant if you acces your site with http://example.com/, http://www.example.com/, https://example.com/ or https://www.example.com/ or for mail with imap.example.com or smtp.example.com (or similar). If you are the owner of example.com, no one else can host content that is reachable under a subdomain or with a special protocol.

Would you show us a link to your domain for further checks?

I contacted my hosting company and they say I would need a SSL certificate to stop this happening? I don't have or plan to buy a SSL certificate for my forum, I don't see the point.

To be able to offer your website under the protocol "https" a certificate is mandatory. If you have to pay for it is a question for your hosting company. Most of the hosting companies in Germany offers free of charge certificates from Let's Encrypt at least for the main domain name.

Tschö, Auge