Hi There.

I think it is like this if you need to add subdomain.

Login with your username and pass word

step- 1 look for the place says "website"
click on it.

Step- 2 Look for where it says "Build a website"
click on it.

Step- 3 Cheak where it says "Use Subdomain"
Click on it

I hope that it
I felt the same before I found it.