At the moment you create a turtle, you can give it some commands, so, if you want to get TWO turtles -- one red and one blue, you can use this code:
crt 1 [
set color red
]
crt 1 [
set color blue
]
Notice that if you do the following, then all the turtles will end up being BLUE, since it asks ALL the turtles, not just the last turtle that was created, to turn blue.
crt 1
ask turtles [
set color red
]
crt 1
ask turtles [
set color blue
]