You define the manwin parameter in the definition of the Query list itself:

Then you can define your query code in the DQUERY manwin type and set the parameter to the name you gave. In this example it would be "MYQUERY".

In the body of the manwin you just type the query you want:

SELECT <columns> FROM <table> ...

Note that currently (as of 2019) this menu type is only available for the C++ MFC target. For other platform like MVC its preferred you implement this kind of functionality as a view for better portability and column formatting support.