When you have your registration Form created or if you want to see how the changes you've made affect the form you can "Try Form" to test it out.
Select Registration from the left side navigation menu
Click on the Form you wish to edit
Select Try Form from the upper righthand corner of the registration editor.
Work through the registration form like a normal registrant would
Keep in mind that if you fully complete the form you will see yourself as a fully registered participant in your participants list. If you wish to delete yourself from this you can go to the participants list, select yourself and click Actions