If you close your browser window while registered for a Tournament, without exiting to the Lobby, then you will be dealt in when the Tournament starts. After timing out on your first turn, you will be sitting out, and your hands will automatically be folded until you return. You will still pay the blinds and antes from the chips. Rest assured, further money will never be taken from your playing account balance, just the initial buy-in that you chose to spend at the start.
You can return to the Poker Lobby, locate the game and re-join, if you still have chips on the table. If you do not return before you run out of chips, you will be eliminated from the Tournament.