Over the last year or two, any site that didn't move entirely from HTTP to HTTPS may get warnings in browsers like this. It's NOT YOU. It's just their site may not have completed the move.
If you feel you need more of an answer, contact the site's owner or web master.
I have used a tinypic for two or three years. I'm a registered user, have username and password, don't remember if I paid anything for this. I used to use it to upload pictures onto a forum which was convenient. And I also use it to upload smileys or emoticons, for which it has a very convenient procedure. And in fact I store the smileys there, I collect them as decent ones are increasingly hard to find, but that's another forum question.
When participating in forums using the iPad it is easy and convenient to slap a smiley from my collection onto a post of mine. But it is very difficult on the iPad to add a new smiley into my collection, it doesn't seem to work. I used to upload them much more easily using my computer (Mac 12" notebook, Hi Sierra 10.13.5). But now when I go to log in I get the warning 'Website not secure'. Something I don't remember happening often for other sites.
This is a very well-known website and facility, so what do I risk? Need to take seriously?