Step::1 Log in to your Client Area.
Step::2 Click on your username and select Contacts/Sub-Accounts option from the drop down.
Step::3 On the new page that opens, fill all the necessary details and assign required privileges to secondary account.
Step::4 Tick to Activate Sub-Account option to provide client area access to this sub-account.
Step::5 After filling up the required details of sub-account, click on the Save Changes button.
That's It !
Go through the video tutorial to know detailed procedure of above mentioned steps. You may read the blog as well.