Another 2 miles after Vernal Fall (and up some pretty steep, rock switchbacks) you will make it to the top of Nevada Fall. The best spot for photographs is about half way up the waterfall, and should be fairly obvious.
Once you reach the fork at the top of the climb, turn right for a short trip to the top of Nevada Fall. If you are continuing on to Half Dome, hike back to the fork and continue straight ahead and you will soon enter Little Yosemite Valley. If you are hiking the Mist Trail, continue back down along the John Muir Trail towards the footbridge.