Appeal as a member.

Basically, you write here what you think you could contribute to the development team.
Criteria:
Who you are (In a nutshell, we don't want to hear your life story)
Any useful skills (again, please keep it to the required areas)
Anything extra you think you could add.

Example:
Hi, I'm (first name here, OPTONAL) and I have done (programming, art, etc.) for (insert time frame)
I think that I am able to bring some good (skill here) because I have experience in it.
(random stuff, but don't go off key)

And then I'll get the admin to have a look and see if you're a suitable candidate.
Good luck!