Once you have authenticated as an administrator, go to the Dataflow view and click on instance management.

Then click on the top right button to create a new instance.

You will be shown a form that must be filled out completely for the instance to function properly.

You have more information on how to select a default instance in the following link:

Changing default instance

You have more information on how to assign an instance in the following link:

Assign instance to user

You have more information about user permissions in the following link.

On User permissions

Click on the lower right button to finish and the instance will be ready to use.

You can read how the instances work in the following link:

How instances work