Tim go to your dashboard.
There will be a menu on the left hand side (sorry, I cannot upload images).
If Yoast SEO has been activated it should show up somewhere in that menu (about half way down).
If not it may need to be activated. Go to "Plugins" > "installed plugins".
This will give you a list of ones currently on your site (plugins are little bits of software that are added into platforms such as Wordpress (yours) or say Joomla).
If necessary, click the "activate" link and see what comes up. If it's the free version, that should be it (no inputting a licence number).
I do not use Yoast anymore but from memory, the boxes to be filled should appear below the individual posts or pages (titles, description, tags AKA keywords).
Fill these in and then press "update" in the top right hand side of the page. Don't keep updating every couple of minutes. This is because everytime you update Wordpress, it "pings" the search engines. Do it too often and they do the robot version of get p-ss-d off.
Sorry, posts and or pages will be towards the top of the left hand menu. You need to open each one up by clicking "quick edit"
See how you get on.
Also....
1/ Go to "settings" > "reading" and make sure this box is not ticked.... "Discourage search engines from indexing this site" - you may be accidentally blocking the search engines from crawling your site.
2/ Go to "settings" > "permalinks" and check the "postname" box. That will give you much more SE friendly post / page URLs
That should keep you going for a while!
