You need to plant two different varities to allow cross pollination. Each will have both male and female blossoms, but with the rare exception (I think maybe sunflower) pollination by a different variety or maybe tree is required. Hand polination is most effective, but I have read stories of hanging meat in a tree to attract flies to support pollination. I have two varieties of petterson paw paws in their second full year, so I have no first hand experience.

Go out on a still warm night when the first flowers are starting to wilt/drop. You should see gnats/ants on the ripe flowers. If not you might want to try hand pollination.

Scott

The flowers are perfect,being male and female,but start out as female and then later develop into the male with pollen.
Like Charlie wrote,it is best to have two different varieties. Brady