Once you've created created your scheme(s) you will want to set your default settings.
Click the employer name in the main menu and choose "Edit Details". Click on the 'Pension' tab.
If you select a scheme here then all new employees you create will be instantly enrolled on the scheme as soon as you create them.
Most employers would leave this set to 'none'.
Here you can select which scheme should be used when an employee is being assessed as needing to enrol on a pension.
There are also other option related to auto-enrolment such as your staging and cyclical re-enrolment dates.