Update strSQL with input box

Experts,

I am using the code below to add X number of days to a [DueDate].  I want to make it more dynamic and i/o having numerous buttons on the report for Adding 1 Day, 2 Days, 3 Days to the [DueDate] I would rather have an input box.  I thought I could add the bolded areas below i/o having a hard coded number.

I get an error with the below.  
How can I do what I am proposing?  

thank you
 
        Dim strSQL As String
               strSQL = "UPDATE TASKS Set DueDate = DateAdd('d', [Enter Days to Add], DueDate) WHERE  status <> 'Completed' AND DueDate= Date() [Enter How Many Days Ago]"
           CurrentDb.Execute strSQL, dbFailOnError
            Me.Requery