Plan on running four to five times per week. Two to three of those runs should be at a pace where you can speak at least in phrases or short sentences. One of the runs should be a long run (increasing the distance every other time) done at a pace where you can do long sentences, and one should be an interval run. You can also substitute fartleks and hills for the interval.
An interval run consists of running fast a number of times over short distances, with a slow jog for recovery between the fast runs. Consider you run on a track - do 1/3 the distance as fast as possible and then jog back to the start at a very relaxed pace. Repeat. In the beginning, you may be able to do this no more than 2-4 times. Over time, you will be able to do it 8-10 times. You will get faster and your endurance will improve.
The long runs are also excellent for building endurance. If you can do a 3 mile jog presently, one possible long run schedule would be:
Week 1 - 5 miles
Week 2 - 4 miles
Week 3 - 7 miles
Week 4 - 5 miles
Week 5 - 8 miles
etc.
You might top off at a maximum long run of 12 miles unless you are training for a marathon.
NOTE: A fartlek run is basically done at a regular run pace with bursts of speed built in. See
http://www.time-to-run.com/training/...ek/session.htm
There are a number of good websites with running plans. Another example is at
http://www.runnersworld.com/channel/...nel-_-Training
Good luck and have fun