How can I get a macro to run by clicking in a cell.

I have numerous columns of data. When I click in the column title in row 4,
I then want the data in rows 6 to 314 in that same column to be copied to
column D. (From there it feeds through to a report sheet). I have created
the VB for the copying and it runs fine whenever a cell in row 4 is
selected. But I cannot get it to run on its own simply by selecting the
cell.

How is this done please?

Thank you in advance

Peter