You are correct - you need to base your form on a query.
Create a new query, including all of the pieces of information that you want to see on the form. Make sure you include the date field. Use the query wizard to help you set up the query. Once you have a query showing all of the records, go into the query design screen and under the date field, enter the following criteria : >=DateAdd("m",-5,Date()). Save the query.
This query should restrict the data to records with a date greater than or equal to today from 5 months ago. If this is not what you want, post a reply.
Use the form wizard to help create a form, based on the query you saved before. The wizards are quite easy to follow but if you get stuck post a reply.