batch size

if i want to end up with a five gallon batch how much water should i start with for a full boil....and what amount should i put into the pro mash program?

6 is a good starting point

so in pro mash for batch size do i put 5 or 6 gallons?

I haven't used pro mash, but it seems logical to specify the final volume you want to put in your fermenting vessel. 5 or 5.25 gallons, or whatever your target fermenting volume is (I like 5.25 to 5.5 so I still end up with 5 gallons after losses due to SG readings and racking to leave trub behind, etc).

You start your boil with more water than your target wort volume because you know you are going to lose volume during the boil. I am sure I lost more than a gallon in an hour boil on my last brew. You might figure on 5.25 final wort volume and start with 6.5 gallons of wort in the boil. Just a guess. You'll have to adjust for your conditions, expectations, and length of the boil.