Only account owners can add new usersIf you're not the account owner, you won't have access to create users. You'll need to ask your account owner to add a new user for you.
Seeing the 'Your team' option?This means you're a top account owner and you don't belong to any other account. In this case, go to Managing your team to read about adding a user.
You're able to add extra users to the system under the control of your account, enabling you to manage them and ascribe them various permissions. This is useful to allow a number of people within your team to use one centrally managed account without having to sign up for multiple full accounts.
Adding a user
To add users to the system, mouse over the person-and-cog icon in the bottom left corner of the screen to produce the settings menu. Select the Access option.
The screen displayed will detail any users with access to the system.
Click on the New user button to display the screen that allows you to add a new user's email address and set their permissions.
For more information on the permissions, mouse over the available tooltips.
When happy with the settings, click on the Save button.
You will be informed that the added user has been sent an invite to join your account. They will need to click on the link in the email they receive within 24 hours and complete the details they're asked to provide, after which they will be displayed in your list of users.
If an invite expires, you can re-invite the user again.