How do you flirt with a guy who knows you like him and get him to fall for you?

Just giggle, be smiley. You don't want to get preoccupied with 'flirting'. Just be genuine, when the 'honeymoon' stage of the romance wears off, you want your potential partner to see the 'real' you. Have integrity, be honest, and be sincere, it'll work great.
Well to start off you should improve your spelling and sentence composition. Its not faling its falling. And its not "How to get a guy falling for you?" its "How to get a guy to fall for you."

Find out what guy's interests and hobbies are. If he like football go to google and study football. WATCH the game. Learn the rules. Pick a favorite player. Pick a favorite team. Pick a player and a team that is not well known. If you pick Tom Brady and the Steelers then you will seem like your jumping on the bandwagon. Look up his Facebook profile. It can tell you a lot about him and what he's like.

TALK to him. When your walking by him drop your backpack and let all your things fall. If he is nice then he'll help you pick them up and you can start a conversation with him. But if he's an donkey then he'll just ignore and so he's not the good guy.

Also look at his friends. Are they all of some ethnicity or social stature. Talk to his ex girl friends. They can tell you a lot about the guy.

Good Luck!

JustChillMan