I have used the partner finder here to locate if there is any climbers around town. But I wonder how exactly do things work normally? Do I send the person I want to climb with an email or just post an ad on the forum?
Post in the partners forum: where you're climbing how long you're going to be there what gear you have what you would be psyched to climb leading and comfortable following ability
and then here's the kicker,
DON'T FLAKE
I've met many amazing people through MP. Use it. It works.
Add your name to the partner finder database, update your profile to include some info about your climbing ability, age, and other stuff, and use the tick list and to-do list to give people an idea of what you like to climb. Then post on and read the partner forum to find people who are currently actively looking for partners.
Oh yeah, what alpinista83 said, please don't flake.