When you install a SSL Certificate on to your web server or hosting it makes your server capable of accepting secure, encrypted connections to your website, however yourself website itself needs to be programmed in a way so that it knows to make use of the SSL Certificate.
For example on your website if you have links to pages that begin with http:// they will go to a plain / unencrypted connection, those links should be replaced by ones that start with https:// instead.
You may wish to roll out SSL throughout your website and there are various different ways of doing that within WordPress, one method is to edit your WordPress configuration file (which is called wp-config.php) and add the following two lines to it:
We would advise trying the above code first however if that does successfully convert all of your WordPress website to SSL then there are other means you can use. There are free WordPress Plugins available which will offer to fully SSL enable your website, please note they do not obtain a SSL Certificate for you (you will need to purchase one first) but when you do have a SSL Certificate installed on your web hosting then you can look at enabling SSL on your website.