assuming 1 box (calling it colourbox) I would use a case like
Select Case txttot.Value
Case Is < 201
Me.ColourBox.BackColor = 255
Case 201 To 400
Me.ColourBox.BackColor = 38620
Case Is > 400
Me.ColourBox.BackColor = 65280
Case Else
Me.ColourBox.BackColor = 16777215
End Select
but don't forget...