Here is some code that might help.
Check out the LoadPicture to do the loading of the image on the CommandButton.
Private Sub CommandButton1_Click()
Dim picks
Static marker As Integer
picks = Array("c:\Documents\GH Up.jpg", "c:\Documents\GH Down.jpg")
Select Case marker
Case 0
marker = 1
Case 1
marker = 0
Case Else
marker = 0
End Select
CommandButton1.Picture = LoadPicture(picks(marker))
End Sub