Your subdomain can be your business name or your name.
Step 1: Click the Account Settings icon on the menu to the left.
Step 2: Under Personal Information, click the blue Edit Profile button. Additional fields will appear where you can fill in the various details of your account.
Step 3: Enter a new, unique subdomain. If it's already taken, you won't be able to save it. Edit any other fields to suit your needs.
Step 4: Click Save.