Securing your WordPress site is quite simple. After your secure certificate is installed, go to Settings > General. There are two blanks for the WordPress address and the site address which may be the same. Just add in that s to http in both and save.
If your site has switched to mandatory SSL, you’ll have to make those changes in the database. This really isn’t hard but can be scary. If you can access phpMyAdmin (cPanels all have that link – some hosting companies hide it), go to your blog database and edit the wp_options table. Both of those links are there with the wordpress setting near the top. The home address setting is more often on the second page.