If you have a smartphone, I highly recommend a couch to 5K app. It starts you off alternating just a minute or 2 of running at a time with walking, then builds the running time up. I started it mid-June, and am almost there. It's supposed to take 8 weeks, but I repeated workouts on purpose to go easier on my knees and feet.
If you don't have a smartphone, you can probably find a program and do it on your own with a stopwatch. The app makes it so easy, though - just start it up and go run.