Do you know you can get a Letsencrypt certificate for free?
Let's Encrypt Certificate of Authority SSL
Also, you can get rid of that yellow warning triangle on top. The reason the warning triangle on top appears is because there are images using the "http://" extension instead of the "https://" extension. One way to get around this is to remove the "http" extension from the code.
When the browser call the link, it will substitute it for the right extension, "https:"
The same goes for images;
<img src="//somelink.com/folder/imagename.jpg" bla, bla, bla...>