Migy, Hi - and welcome. Standard practice is to add water at about 3 times the volume of honey. So, if 1 lb of honey is about 10 fluid oz then you want to add about 30 fluid oz of water for a total of about 40 fluid oz. (or about 1/3 of a gallon).
That said, a better approach is to measure the specific gravity of the mixture of water and honey. When properly mixed that solution should have a "gravity" of about 1.100 and that will give you (potentially) a mead of about 13% alcohol by volume. That will be very dry (not sweet) and what most experienced mead or wine makers do is when the mead or wine has fully fermented and they want the drink to be sweet rather than dry they will eliminate the ability of the yeast remaining in solution to continue to ferment (this by stabilizing the mead or wine by adding two chemicals to it - one called K-sorbate and the other K-metabisulfite) and then they add as much honey or sugar or maple syrup or agave or any sweetener that they like so that their product is as sweet as they want it.