First let's clarify the question (As you manage to contradict yourself). I suspect you mean the selected date and the previous six days making a total of seven days. I will work to that assumption.
You can cause an Access query to prompt for information by referencing something in square brackets [] that is otherwise unknown. Also, multiple references to the same enclosed text will only prompt the once.
So, for the requirement specified you want a query whose SQL is of the form :
- SELECT [YourTable].*
-
FROM [YourTable]
-
WHERE ([YourTable].[SomeDate] Between DateAdd('d',-6,CDate([Please select date])) And CDate([Please select date]))