The How to Play section is a menu option. It has information on the game on how to play the game. To get to the next page press left. The description says 4 seconds, but my advice is to stay on each page 5 or 6 seconds so the game registers you staying on that page for at least 4 seconds.
After going through all the options under the how to play section, if the trophy doesn't pop for you, you will have to start over. The only way to keep track of which pages are done is to keep track yourself. Happy gaming!