Would like a Macro that would use a dialog box to ask which column to use and than what number (value) to copy down what ever number of rows there might be.

I have regular jobs where I get a number of excel address lists that I open, go to the last column, place the word List on the header cell, then copy a number (same number) down the column to the last row with data. The first list would be 1, the second list 2 and so on. The column isn't always the same so what I would like is a Macro that would open a dialog box asking me the column letter which I would enter, then ask me what number I'd like to use, then have it copy that number automatically down the column to the last active row. How that makes sence.

Thanks in advance
Purcell-Test_10.xlsx