Let's take a quick look at how to use Donesafe's People Selector.
In this example, I am using an Action but really the behavior of the people selector is the same throughout the product.
To choose an existing user in people selector, type the name into the box. Once the user's name appears, simply click to select that user.
Located at the righthand side is the add new user button, this allows you to add the person that doesn't already exist within the system.
Bear in mind that you should only do this if they ARE NOT already a user. In most cases, you'll just be able to lookup an existing user by using the search filled.
It's that easy.