I grow 8 varieties, and have so many now that I don't even harvest them sometimes- they are taking over my yard (most are about 10 years old or older).
Anyway, pick them when they are perfectly ripe, when they are papery and dry, but not browned. They should smell great when you pick one and rub it between your hands, and have full lupulin glands- those yellow full sacs along the base of the leaves.
I dry mine in a warm dry place with fans blowing over them, while they are in screens. They should lose alot of moisture, and weigh about 1/6 of what they did wet. Then, I weigh them into 3 ounce size portions, and vacuum seal with my food saver and put them into the freezer.
Once they are dry, you want to protect from heat and oxygen.
If you want to try wet hopped beers, you will need to use them within a day or two of picking, and use them just like that. Because of the water weight in them, you will want to use about 6 times and much as dried hops.
Lots of people love wet hopped beers, and if you have a brewday around harvest day, you could try it for yourself.