Defining Criteria on a subject is a way of controlling the data that users will be able to extract using the queries they build on that Subject.  If you do not wish to define any Criteria move onto the Subject Wizard - Select Fields form by simply clicking on the 'Next >' button.

.

If you do wish to define criteria, then click on the 'Add' button to bring up the Subject Condition form which will guide you through building the conditions of your criteria.

If you wish to Edit or Delete any of the conditions which make up your criteria, simply click on the condition in the list view to highlight it, and then click on the 'Delete' or 'Edit' button.  If you click on the 'Edit' button, the Subject Condition form will be displayed to allow you to make your changes.