If it's a new form, use the form wizaed to create a form, and in the stage
when yo need to select a table, select the query you want, that way the form
will be created bounded to the query.
If you want to use the query in existing form, open the form in design view,
open the form properties, one of the properties call RecordSource, locate the
cursor in it, on the right you'll see a button with three dots and a button
(combo like) that will display a list with all the tables and select queries
that you have, select the desired query.