Straight down from the Don's mansion is where you go to learn about the passes. One screen to the left is where you buy them (you have to go around). Lin Lin's massage parlor is where you figure out how to make them actually useful.
BTW, once you have paid for a good pass at least once, you can use it as a reference to try and turn poor quality passes into good ones yourself. Combine an ink pen with a poor pass at the table in your condo / farm side room / Cassie's place.
Although, it requires a fairly high Nimble stat to reach 100% chance of success (26+ I believe).