Open your pgn in a text editor, (notepad). Selaect all the text, and copy to the clipboard, then paste it into the pgn window. Easy :)
Chess game to a forum topic?

If it is with the board, Come on now, the easiest way doesn't even use PGN?! Just copy all the moves of the game, Click "insert position or game" At top left on where you will type, Click
Game or sequence of moves, then start on a blank chessboard,click enter moves and you have now what we call a chess game. just move the pieces.
If it is not, follow rooperi.

If it is with the board, Come on now, the easiest way doesn't even use PGN?! Just copy all the moves of the game, Click "insert position or game" At top left on where you will type, Click
Game or sequence of moves, then start on a blank chessboard,click enter moves and you have now what we call a chess game. just move the pieces.
If it is not, follow rooperi.
It depends. If there are many moves it's easier to download png.
Thanks everyone
I would like to know how to add a chess game into my forum post. I see that I need PNG file (which I have), but it seems that I can't open it.
Do I need to install a software for opening png files, or what? Is there and easier way?