There are two ways to install a theme.

1. The first way to install a theme is by using the Admin Console.

Navigate to

Admin > Themes and Layout

At the bottom of this page you will see



Click on browse and upload the theme.

Now your new theme is installed, but it isn't going to show until you navigate back to

Admin > Themes and Layout

And you will see this:



Change both the "Overall Forum Default" and "Reset Everyone to" fields to the theme that you just installed.

2. This is an alternate method to install themes, this is particularly useful when installing large themes

What you do is download your theme and unzip it on your computer. Then using an FTP utility like Filezilla you will upload the new theme folder to your server in the "Themes" folder.

Then navigate to

Admin > Themes and Layout

And at the bottom you will see:


The area where it says "From a Directory on the Server" will look something like this
/home/content/html/Themes/

What you will do is put the new theme folders name at the end of ..../Themes/

So say your new theme is Lazy_Daze then it would look like

/home/content/html/Themes/Lazy_Daze

And then click install :)