Hi Crooknees
The whole of the internet is moving towards https. http is "Hyper Text Transfer Protocol" which is the protocol (language) that has been used for web browsing since the world wide web was created. Https is the secure version where your data (including passwords) is encrypted (scrambled). Generally modern web browsers (Chrome, Safari, IE, Edge etc) show a green padlock in the address bar when you are connected to a trusted https site (trusted insofar as their encryption certificate is known to be good). You should never enter your card details or any sensitive information into a non trusted site.
Since a recent upgrade Firefox warns users if the site is not using https, which is what you are seeing.
For sites like ours and many others the risk is very small. Somebody could tap into our traffic and extract passwords. The CIA or GCHQ could park outside your house and snoop on your Wifi. The risk is greater if you use free and open wifi in public places, because you don't know who else is connected to that wifi network and what they might be snooping on.
My personal opinion is that a sewing forum is unlikely to attract the attention of serious hackers. The trouble we and all forums have is people try to get in so they can use the email server to send spam. That is an age old problem (and why we don't do automatic activation of new accounts)
The best thing you can do on the internet is use strong passwords and (excuse me for shouting) DON'T USE THE SAME PASSWORD ON MULTIPLE SITES!
However, we don't want to put people off when they find us with messages that are worrying, and are therefore looking into moving to https. It requires us to apply for an encryption certificate and once issued we have to apply it to our domain - so it's not something we can just switch on.
In the meantime please don't worry. I'm happily here and not concerned about my security. I also use a cycling forum and a sailing forum. Neither are using https, nor does Stitchers Guild Reloaded.
The Google advice on this issue is
here.
Hope that helps
Andy