Quite an easy achievement. During the game, press 'Y' to get the historical facts up (you'll also be prompted to press it on occasion, and can access from the pause menu).
Any facts that are unread will have a exclamation mark next to it, simply scroll down over them for the game to count it as read.
EDIT: Should mention that there are only a certain number of facts per level available to view, usually relating to the level in some way. Just press 'Y' at the beginning of every level and you should have it by mid-way to late chapter 2.