Fields are represented by the green text entry boxes. Simply pick and edit a box for it to be folded into the current query command. For the numeric entries, the user will receive a warning that the syntax is not numeric, which can be ignored at the user's choice. Click the Search Locally button to search. Each time you click here you will execute whatever query you have built.
Tags are the labels adjacent to the fields.
Clicking once on the tag specifies it must be present. It will be highlighted. Clicking again deselects the tag. To select another key set, pick it once or use the New KeySet command. By-Example window will be shown on a command edit line there.