1. Take an old plastic garbage can and drill a dozen or so holes in the sides.
When you add poop to the bin, sprinkle in some septic starter (available at hardware stores) and add some water.
“Within 48 hours, the septic-tank starter  (which is noncaustic and promotes natural bacterial growth) will have begun its work and you can add more dog doo,” explains Michael Levenston, executive director of the City Farmer program  in Vancouver, Canada, from which these instructions are adapted. “You can then begin to add it daily. This waste biodegrades and flows into the subsoil.” (Do NOT use composted dog waste in your garden.)
While burying a garbage can to compost dog waste might seem like overkill if you live near the woods or close to a patch bushes, dealing with dog waste in an environmentally friendly manner is always a good thing.
By the way, if you know someone who lives in a city, the cityfarmer.org  website is loaded with all kinds of helpful urban agriculture tips.