If you have already unlocked the "Best Class Ever" achievement, then you should have a good understanding of how to get ranked #1 in recruiting class. If not, then I suggest you head over to that achievement to find out how. You will need to do the same process when going for this achievement.
After completing your recruitment board, you will either need to simulate the season or play the games individually. I suggest playing the games since you could end up losing to teams when simulating the season. But if you are simulating games one-by-one, then make sure you turn off Autosave from the 'My NCAA > System Settings' menu.
Simply simulate or play the games until you reach the BSC bowl. You can either play the bowl or simulate it but just make sure your team wins. After winning the bowl you will need to progress onto the off-season. Simulate up to Signing Day and the achievement will unlock.