Log into your back end of your website
On the WordPress tool bar go down to Appearances and select themes
Select add new
Here you can either upload a theme you already own or install one of the many themes in the library
You can browse through themes using the helpful toolbar found on the top of the page.
You can search through the various options or if you know the name of the theme you want you can use the search bar on the right
Once you have found your theme you want you can either view details and preview or install the theme
If you preview the theme you will be brought to a page like this
Lets install the theme
Now the install button will change to activete
Lets go ahead and activate the theme for our website
Once activated your theme has been installed.