I'm not familiar with ChessProgram 12, but if you can copy and paste the contents of that file, that's all you need.
PGN file

By default, your Chess Program 12 files are in ChessBase format, but they can be easily converted to PGN (which are text files).
In the game list, right-click the game and choose output > selection to text file. In the pop-up, choose pgn. Save the file where you can find it.
To post here:
Open the file with Notepad. Copy and paste.
how do you upload a PGN file on ChessProgram 12 onto here? Thanks.