The usual placement is 2-3" feet from the house (usually just under the roof drip line) and space them every 10 feet, give or take a few inches. It totally depends on how many linear feet of ground you have around the house. Measure the house, or walk it off and find out how many feet or what the distance is around the outside of the house. If the house is 130 linear feet you will need 13 stations (approx). If it is more or less then you can decide.
Most houses need at least 15 -20 stations. Less if slightly smaller.