All the guppies in all three pictures appear to be male. What you are looking for is the "Gonopodium" which is the male reproductive "fin" on the bottom.
Basically - male guppies' bottom fin looks like a hangnail, where females have a regular triangle bottom fin.
"To know that we know what we know, and that we do not know what we do not know, that is true knowledge." -Confucius