**Note if you are not an account administrator or if you are on a free account, you will not have any licenses to assign.
If you are an account administrator with licences to assign you can add users to your account by navigating to your Options on the left side panel. Select Manage Users in the top right corner. Here you will find the number of licenses available to you, and the number of licenses left to distribute.
You may add users directly from this page by clicking the Add Users button and filling in their contact information.
See how to remove users from your account here.