Two Ways
First is through the Form Properties, and see the red box in the attached graphic, the other is through code, which is included on the Form open property, so that i can just change whatever graphic i want per form,
as long as the graphic path is known, and i just keep the graphics in the same directory as the Database i am using.
Private Sub Form_Open(Cancel As Integer)
DoCmd.Maximize
Set dbLocal = CurrentDb()
pstrAppPath = CurrentProject.Path
If Dir(pstrAppPath & "\graphic.bmp") <> "" Then
Me.Picture = pstrAppPath & "\graphic.bmp"
Me.PictureTiling = True
End If
End Sub