The Query Editor provides a graphical way to create and edit select queries without having to know SQL syntax. It especially makes it easy to JOIN tables together via relationships.
The Query Editor has two modes, Visual and Text. The mode is switched via the first two buttons at the top of the Query Editor. Visual mode is pictured above and is where most work in the Query Editor is done. However, you can switch to Text mode if you would like to see the actual SQL that makes up the query, or if you want to manually edit the query. If you do edit the query manually, you will only be able to switch back to Visual mode if MacSQL understands the changes you made.