you have to wait until you become a warrior in the game,
and then go to the dip, you might see crystalblaze and another cat
you have to go to bramblestar after and then tell him
and then wait until sunfall appears when you go to the dip again sometime
and then he says you have to go to the fair
and just keep talking to crystalblaze at the tent until she says something
and then find out the rest, I think I typed too much alr