Telling the difference?

Well first things first i can't find a internet host that i can keep my pictures on for more than 10 minutes seeing that it is considered "illegal". I planted seeds of some sativa about 3 weeks ago, the 2 plants that "sprung" up are starting to form their 3rd stage of leaves. I was wondering how to tell the difference between a male and female, if i even can at this stage. I really don't want to keep on growing them if they are males, i read the sticky from Widowmaker but all of "his/her" plants are damn near full grown in the pcitures. I have read on other sites that basically a male looks like it has a penis and the female has her parts as well. I will try and get some pictures to hold up...until then thank you for the help and or info. Description of them is below:

Height: 4"

Leave: 3 branchings

Growning out-doors, wanna do the "natural thing"

Holla

B

You wont be able to tell yet........sorry

Well thats actually good to hear. I'm having a good time watching and waiting...Do you by any chance have any clue as to when i might be able to notice? Or will it be more towards the harvest time, like 5 months from now?

In veg it depends on when the plants mature but for a beginner it would be easier to tell after you switch your lights to 12/12...