need a command button to change / unchange the colour of specified cells

[fingermouse]

Hi,

I'm a complete novice with macros so please forgive me in advance!

Hope someone can help me with the VBA code required.

Please see the attached file...

I've assigned a command button to a macro but I cant get it to perform as required.

What I require the macro to do is this - When the command button is clicked, specified cells change from no fill colour (which should be the state when the excel file is opened) to a yellow fill colour. When I click the command button again, the cells return to no fill colour.

Does that make sense?

Below is the code I have. I know its a load of rubbish, but to be honest I haven't a clue what I'm doing!

Sub Macro1()
'
' Macro1 Macro
'
' Keyboard Shortcut: Ctrl+Shift+A
'
    Range("B11,B13,B17,D11,D15,D17,D21").Select
    Range("D21").Activate
    With Selection.Interior
        .Pattern = xlSolid
        .PatternColorIndex = xlAutomatic
        .Color = 65535
        .TintAndShade = 0
        .PatternTintAndShade = 0
    End With
End Sub

Any help would be much appreciated!

Best Regards,
Cal