Your question is unclear, but I will give some different answers based upon scenario.
Dump boxes in general are designed to hold 6 cartridges of the correct caliber in a HORIZONTAL position inside the dump box. Thus, if it is a double dump box, it holds 12. A single will hold 6.
If the dump box has a hinge, you position the box so the snaps are at the top of your belt, so that when you unsnap, the dump box swings down on its hinge to release the cartridges.
If the dump box does not have a hinge, you position the box so that the snaps are at the bottom of your belt, to allow release of the cartridges by gravity through the open bottom of the box.
You can carry the box either to the right, or to the left of the belt buckle. Assuming you are right handed, the bullets (projectiles) should, from YOUR perspective, point to the LEFT, so that when they are released into your hand, they are pointed in the direction they need to go with respect to loading the cylinder of your revolver. To clarify, if you are right handed, and the dump box is between your revolver and your belt buckle, point the bullets toward the buckle. If the dump box is on the opposite side of your belt buckle, point the bullets the SAME direction, which would be AWAY from your belt buckle. In either case, when the ammo is released into your hand, the cartridges are pointing toward the charge holes.
Remember, when using the device, that the correct method is to shift the revolver to the LEFT hand (assuming you are right handed) to open the cylinder and eject empties. The revolver stays in your left hand while your strong hand (right hand, if you are right handed) manipulates the cartridges. This procedure would be reversed for a lefty.
That said, the dump box method is slow, and several loose cartridges in your hand at a moment of stress means you are likely to drop cartridges. Personally, if you do not want to use speedloaders, then I believe the preferable way to carry ammo is either on a speed strip inside the dump box (Tex Shoemaker makes the Model 207 for just this purpose). Ordinary dump boxes are not long enough horizontally to allow the speed strip AND the cartridges, so you have to have one made especially to include the added length of the speed strip. If you do not use speedloaders, or strips, then I think the preferred method is a 2x2x2 pouch or old-time loops, which allow you to grab only one or two rounds at a time, which are less likely to be dropped when you are in the middle of a gun fight.