Generally juice concentrates are the easiest to add, though crushed fruit would work also. If crushed fruit is used, the juice should either be well strained before hand, or the mead should be racked within the first 7 to 10 days after starting the ferment. This will prevent any fruit matter from spoiling along the bottom of the vessel, tainting the mead. I'll take a moment to mention that five pounds of sugar. It needs to be well dissolved, with no free crystals sitting in the bottom of the fermenting container.
Some people add all the sugar right in the beginning.
Other add it a pound or so at a time as the yeast ferment it. The reason for this is that a high sugar content can inhibit the yeast to a certain extent. I personally find it simpler, and no less effective, to add all the sugar at one time. Stir well again. This will sterilize the whole mix rather nicely.