how do I find helipads?

There are heliports what show up as "H" on the map and there are helipads on existing airports. Click on the airport and on the airport diagram there will be an "H" for each helipad.

There are helipads now at a lot of airports, but not every real world airport has one, so you won't find one at every airport.

Places you can try: San Francisco Bay area, you should see at least two heliports there.

If you don't see any in the location dialog then please do a game file integrity check in steam.