Properties
Enter the Element Type's name, key name, and a brief description. The key name should be unique, one-word identifier. Choose a type of Burner for your templates to use. When adding a new Element Type, you can also select the Element Type Set.
Group Memberships
Groups determine the permission that users will have to read, edit, or create Elements Types of this kind. Select a group from the 'Available Groups' list and click the 'Add to List' button to add it to the 'Current Groups'. You can remove a group from the 'Current Groups' by selecting a group and clicking 'Remove from List'. If you are creating a new Element Type, click the Next button to continue. This will bring you to the full Element Type Profile.
Sites
Top-level elements (story and media type elements) can be shared among several sites. This section won't be present for non-top-level elements. The Sites section allows you to add or delete sites from the element. You can also select the Primary Output Channel for each site.
Existing Subelements
Elements are really containers for other elements as well as data fields. To add subelements to an element, click the 'Add Subelement' button to bring up the 'Choose Subelements' screen. Use the Search box as usual to select all or a subset of the available subelements. Naturally, the elements you can select won't include top-level elements. To add elements, check their corresponding 'Add to Element' checkboxes, then click 'Add Elements'; if you decide you don't want to add any subelements, just leave all the checkboxes blank and click 'Add Elements'. This will bring you back to the Element Type Profile.
Custom Fields
Fields are where data is stored. Along with subelements, these define the structure of an element. In the Custom Fields section you can edit the default value for the field. You can reorder the elements by selecting a number from the popup menu. To edit the field, click the Edit link. This will bring you to the Field Profile, where you can change anything about the field except its key name and type (text area, checkbox, etc.). Finally, to delete a field, check the 'Delete' checkbox and click one of the Save buttons at the bottom.
Add New Field
This is where you add new fields to the Custom Fields section. First, choose the field type from the group of checkboxes on the left. Through the magic of JavaScript, this will change the available attributes on the right depending on which field type you choose. The attributes are explained in detail on the Field Type Profile Help Page

When finished, click Save, or click Save and Stay to save but continue editing the Element. Clicking Return will bring you back to the Element Type Manager without saving your changes.