How do you get Rock Climb in Pokemon Diamond and Pearl?

When you beat the seventh gym walk through the snow . The route to get there is through snow and mount cornunt the snow part is were you can find a poke ball that contains the HM rock climb .When you are walking south from snowpoint city there is a few poke balls in one there should be rock climb .I never found the hm fly till I bet the seventh gym and still haven't found defog so I hope you find it.