Can you change the background color for the parameter pop up window. I have query that asks the beg date and ending date but I was wondering if I can change the color of the parameter

You could display a custom input box in the button click event that opens the query. This form could then be of any shape/size or color that you want , and could conceivably allow input of both begin and end dates, have a calender control etc..
The form would take the value input, do any validation you want on the dates (which you can't do in the system parameter box) and store it for use in the query in a global var or property.
If the user chooses cancel, the return value/s might be blank or a default.

so the parameter [Begin Date] inthe query becomes something like =fGetBegindate()

Function fGetBegindate() As Date
fGetBegindate = glbBeginDate
end function

Function fGetEnddate() As Date
fGetEnddate = glbEndDate
end function

Sub Query_Button_OnClick()
Dim bValid As Boolean

On Error GoTo Error_err

DoCmd.OpenForm "frmDateForm", windowmode:=acDialog
If IsLoaded("frmDateform") Then ' routine to make sure it loaded
'... validate txtDate
bvalid = true ' if it is of course
If bValid Then
glbBegindate = Nz(Forms!frmdateForm.txtBeginDate)
glbEndDate = Nz(Forms!frmdateForm.txtEndDate)
' or set the variables in the form itself

DoCmd.Close acForm, "frmDateForm"
docmd.openQuery "Queryname"
end if
Else
' form closed by user
' supply default value if you want
' or just don't run the query
glbGetBegindate = Date
End If

Exit_err:
Exit sub
Error_err:
MsgBox Err.Description
GoTo Exit_err
End sub

Function IsLoaded(ByVal strFormName As String) As Integer
Const conObjStateClosed = 0
Const conDesignView = 0
' Returns True if the specified form is open in Form view or Datasheet view.


If SysCmd(acSysCmdGetObjectState, acForm, strFormName) <> conObjStateClosed Then
If Forms(strFormName).CurrentView <> conDesignView Then
IsLoaded = True
End If
End If

End Function

Note: You can't open a user form from inside a query.