You will get it from your rival at Shalour City by the gate that leads to Route 12.
Surf is HM #3. :-)
Get the HM Surf then teach it to a pokemon.
You get HM Surf and surf there
You need a water Pokemon and the surf HM
Surf is a HM so you can teach it to multiple pokemon.
teach it the HM surf
with TM and hm's
go to celestic town enter in the cave talk to the woman and you have the hm surf
You can get surf in Pokemon black and white by battling Cheren at the Twisted Mountain. Then Champion Alder will give both you can Cheren th HM Surf.
Celestic Town
its suppose to be surf
from the champion's grandma