how to tell if its a roo or hen.

[chicklover1998]

hey I have better pics of chickens and can you tell me if they are male or female. they are all three weeks old and we think that the white one, the black one , and the gray one are males but we don't know and this is my first year so I am clueless.
thanks,
chicklover1998

 

[jamie7100]

Pictures aren't working for me

 

[farmer boy]

same the pics are not working for me either