Even if I didn't have a gf right now, I wouldn't know how to approach a girl on the net.
"So......um....got a photo? I don't date ugliez, not even via email and MSN."
Basically, you'd need to chat (MSN? email?) to somone first, then ask this person what gender s/he is, because it's not easy to tell via the internet. If you don't ask for.....hilarity ensues. After a lot of emailing back and forth, you may end up seeing a photo of this person. When you finally get to see a photo, you'll then know if you just ended up with a new friend, or someone you're actually attracted to. Sounds difficult.