Just press the Select button down for abt 2s, scroll down to the icon where you can see like 2 cams, press select briefly to enter the options and the select "Remote". After that press mode button to return to the LCD status window and you should see Grp 3, A (you can see all the 1,2,3 and A, B, C). This is for working with the D70 flash. Your D70's flash option must be set to TTL Commander mode in the CSM menu.
But the fun really starts when you shoot with multiple SB600s or 800s and experiment. Cuts down the work of going to each flash and dialing in different flash levels manually, just control from the SB800. Esp if your client is paying and you don't wanna look like a dork and waste time. :sweat: