On the left side of the page select 'Website Services' and hit 'Click and Install Apps' In the middle of the page select 'Web Blogs'
After selecting 'Web Blogs' you will see this screen and you have to click 'Install Web Blogs'
You have to enter the required fields mark in red.
Website name: Enter your website name, as soon as you start typing you will see it starts to auto populate.
Installation Preference: Choose Install Application on Virtual Directory
Virtual directory name: Enter your desired directory name. example yourdomain.com/blog
Database Name: You can put _blog
Database Logon : You can put _blog
Password: You can make up a password you will remember.
Confirm Password: reenter your password
Select Database Instance : filled in already
You must put a check mark in the box 'I Accept' and hit 'Install App'
After clicking 'Install App' you will see the credentials and your wordpress url. Save these credentials in a safe place.