Male frogs comes first and try to attract a mate by producing a low purring craok.A male frogs will wrap his forelimbs around the female when mating .
2 Additional Answers
Frogs mate with the male frog grasping the female frog's trunk using his forelimbs. This embrace is called amplexus. Fertilization which happens outside the female's body is called external fertilization. You can find more information here: http://www.backyardnature.net/frogsex.htm
In order to mate, a male frog will sit on a female frogs back and wait while the female frog releases a large number of eggs. While the female releases her eggs, the male coats them in a milky fluid which fertilizes them.