Hey
In your dashboard on the left you should see the following
Post
Media
Pages
Comments
Forms
Appearance
Plugins
Hover over plugins with your mouse then you should see
Plugins>Installed plugins
>Add new
>Editor
Click add new
Then to the right of the page you should see a search box, just type yoast in it and hit enter
In the top right corner of the plugin you want to install there should be a install button, click install
then you should get the following message
Installing Plugin: Yoast SEO 2.3.5
Downloading install package from https://downloads.www.ads-software.com/plugin/wordpress-seo.2.3.5.zip…
Unpacking the package…
Installing the plugin…
Successfully installed the plugin Yoast SEO 2.3.5.
Activate Plugin | Return to Plugin Installer
Click activate and that’s it finished
<<< Make sure you read the yoast instructions/documentation and pay attention, this can negatively affect your seo of your site if you put the wrong content in there
Happy days:)