If you're batch sparging, you can skip the mash out and just do the batch sparge.
If you're fly sparging, you'd add enough boiling/hot water to bring your entire mash up to 168 or so. There are mash calculators online (a free one at rackers.org) or something like Beersmith to figure how much for sure. It's a calculation, and I'm sure you could do it by hand but I'm no math whiz, so I use software to figure it.
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