Dry laying is when you place the stepping stones on the ground without actually fixing them to the surface. This helps work out how far apart each stone should be. To determine the correct distance, make the stones a stride length apart.
To get a neat, even appearance for the path, measure an equal amount of distance either side of the stones.
At one end of the path, line up a post with the outside edge of the last stone. Hammer it into the ground with your mallet.
At the other end of the path, insert another pole into the ground, on the same line as the first pole.
Now tie your string to one post and roll it out to the other pole. Tie your string to that pole, making sure there is some tension in the string.
Using your spade, fill the holes with mortar. Make sure there's enough mortar so that the stones will be level with the ground.