1.) First the bill goes out to the first house if the bill gets the majority of the votes (238 or more) then it passes.
2.) Then it goes to the other house they usually make a few changes and if it does it gets sent back to both houses and if majority rules then it gets sent to the president and he can either veto it or pass it, but if they don't sign it after 10 days it still becomes a law.
3.) If he doesn't pass it, it still has a chance to become a law it just gets sent back to both houses again but this time if 2/3 of people vote on it the bill still becomes a law.