Now on to training - this is as diverse a subject as there are drink variations at Starbucks. So take every training program with a grain of salt and a heavy dose of personal honesty. Back to that personal honesty - if you don't do it now, you will be doing it on race day and that can and will be ugly and I am speaking from personal experience.
Runner's World has a good 9 week training program for beginners - I've used it, it works - it could be better but it's nothing to sniff at. My suggestion to beginners would be to make this a 16 week plan by taking the first 3 weeks and repeating them twice before moving on, ensuring that you feel completely comfortable with the mileage. Then moving on to the next 3 weeks and repeating those 3 before completely the program.
Bart Yasso - who for all you non-runner's is the closest the marathon/race world has of a Clint Eastwood - multi-talented celebrity who isn't flashy - just take my word for it - he has a lovely book called My Life on the Run if you want to check it out - this program is from said book:
Week 1 TWF - 4 miles each day, Sun 5 miles
Week 2 TWFSun 4,3,5,6 respectively
Week 3 TWFSun 4,4,6,7 respectively
Week 4 TWFSun 4,3,5,8 respectively
Now of course there are more than 4 weeks in the training program - you can email me or buy the book.
If you feel you need to exercise more often than 4 days a week - consider making one of the shorter runs a hilly run or adding intervals - but we'll discuss these later. Right now if you are itching for more exercise try yoga, cycling or swimming - all are options for cross training and will respect your knees.
One last thing - REST - resting is not wasted time, it is incredibly important to ensuring you want to run, that you feel like running and that you do not end up injured. If there is a rest day enjoy it.