Using Get Localization Project Sign Up Page
It's recommended to ask translators to sign-up first and create their own account, one option is to give Get Localization -link to project (something like http://www.getlocalization.com/<ProjectName>), they will see sign-up page and can create an account there. You will then receive these requests to your project.
You can then see pending requests in your project Settings, see the application and add or decline the request.
Inviting Users Using User Manager
You can also invite users using the User Manager. See Settings -> User Manager
Just click the "Click here to send an invite" and we will create an account and password automatically and send them to given e-mail address.