Well the first thing I would do is make sure I have the best running shoes for my feet that money can buy.
Then I would begin with brisk walking, 5-6 days a week, for 30 minutes minimum. I'd do this for at least 2 weeks. You can always ratch up the intensity of the walking by walking faster, or better yet, walk in a hilly area if you live where there are hills.
Then I would slowly begin running, maybe 2-3 minutes running and recoverying with 1 minute of walking, again for 30 minutes, three times a week.
As you get fitter, then I'd start to increase the running duration and decreasing the walking resting duration until you get to a point that you are running for 30 minutes consecutively. Again, I'd do this 3 times a week.
After you have at least 2-3 weeks of running for 30 continuous minutes at a respectable pace, then you can start considering an interval workout. Once you are there, post again and I'll give you some sample interval workouts. After you have some
interval training under your belt, then you'll be ready for some sprints. I've had great success with hill sprints. Once you are there, I'll be glad to suggest what you might be able to do.
The short answer, I believe 3 times a week is a sufficient running program with the right intensity, but until you are ready for that, you can walk briskly 5-6 days a week. And you can add 2-3 days of brisk walking on top of running 3 days a week.
But don't neglect a good weight
training program to go along with the walking and running as you'll need both to achieve your results.
I hope this helps. Good luck and keep us posted. Better yet, start on Online Journal and start posting your workouts so we can read about your fitness transformation.