There's nothing wrong with your cert, basically it says that there indeed are some links in your site to the HTTP protocol (http://...). It's easy to find out which is it, just open up the source code and look for some http: link there.
If you're using WordPress, make sure you change the URL of your site in the admin Dashboard from http://... to https://.... If that should not be enough, look at this plugin which seems to fix the rewriting (careful, it says it might be deprecated because it hasn't been updated for a long time, I haven't tried it).
Also, this might help though you already have configured your SSL cert. Go directly to the Configuring WordPress for SSL/HTTPS section.