A do it your self homeowner can purchase a programmable thermostat at a local retail or hardware store. There are a variety of brands to choose from. As a general rule any thermostat available at a retail outlet should come with instructions on setup and installation of the thermostat. Some brands even claim it will only take you half an hour to replace your old thermostat with there new one!
You always have the option to have a thermostat installed by a professional. Some may require you to purchase a brand they deal with. You will have to check around to see what the situation is like in your area.