Short answer: nothing to worry about here!
Long answer: When you browse the web, your computer is communicating with another computer--a server--out on the internet. That communication can be encrypted or unencrypted. Think about it like you're talking to another boat on your VHF. If someone else is tuned to the same channel, they'll hear your conversation. But if you use some kind of secret code that only you and your buddy know, then the interloper won't understand the content of your message, even if they can still hear it.
Same thing with browsing: If the connection between your browser (Firefox, Safari, Chrome) and the server is unencrypted ("Not secure") then someone else on the internet could potentially intercept the data and know what you're posting on the CDSOA message boards. Or they could impersonate the CDSOA website and steal all our varnishing tips. Fortunately, these are not likely to be a serious issues for any of us in the real world.
What could be a problem is if someone watches you log in to your bank account online, steals your username and password, and then uses it to drain your account. That would be bad, and that's a situation where you definitely DO want the connection to be encrypted--i.e. you want to see the little padlock.
Having an encrypted connection never hurts, but it is some added effort and sometimes expense on the part of the web host, so not all websites do it. Keep an eye on the padlock/Not secure notification and make sure that the padlock is there if you're dealing with sensitive information.
