First login to your account from Client Area and choose the "My Services" Link.
Select the service you wish to see details about
Select the "Install Applications!" button.
You will see a list of apps you currently have installed.
Select the "Install New" button
You will see a list of available categories.
Click the blog section to expand it.
You will see a list of available categories.
You will see a list of available blog apps.
Click the "Install Now" link next to Wordpress.
You can then specify your wordpress settings. Be sure to specify the default language, use en for english in most cases. Also you can see in this example we reccommend not using the default "admin" username.
After installation you will see your application listed.