Report to Kadrak at the watch tower in northern Barrens.
Have you ever been to Ashenvale, to the north? The horde has recently set up an outpost on the Zoram Strand there, and we can always use some new recruits to help defend our new fronts.
If you think you are up to it, see Kadrak in the northern Barrens, at the watch tower. He is heading up the Ashenvale campaign and can give you further orders.