there is a board icon on the toolbar when you type. click on it, and you can find many ways to post the games, like posting to pgn or setting up your own position
You click the small board icon beside the test size and input the png
1. Copy the PNG or FEN.
2. Click the chessboard icon above the textbox.
3. Paste the PNG or FEN in the designated area.
4. Profit.
On mobile, I'm not sure if it's possible. You can still copy and paste, but there's no place to paste it that I can see.
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