Database fields
This screen shows a list of all the fields/columns in your selected data. You can then choose a single field so that you can use it with your current control (Text label, RTF, Picture, PDF, etc).
It will also show you the field types, such as text or number and display the data from the first record in your database. You can use the Previous and Next buttons to move between records. It doesn't matter which record you are on when you click on 'Select field'. What this does is to then insert the fieldname onto the previous screen in the format:
<FIELD_NAME>
The <> brackets tell Repeat Signage to treat this as a database field rather than text or a filename.
Picture fields
If you are selecting a field for use with a Picture control, then the field needs to contain either binary image data, or the location of the picture, such as 'http://www.yourwebsite.com/MyPicture.jpg', or 'c:\pictures\MyPicture.jpg'. If the field only contains 'MyPicture.jpg' then you can specify a default location for pictures and other media on 'Template media' tab when you have finished editing this custom template.
Formatting text
If this is a Text Label you are using, then you can use the 'Formatting' tab on the previous screen to control how you information is displayed. For example, you can change words to call upper case, or you can display numbers as currency with currency symbols such as $ or £ in front of them.