What would I tell you?

Hhhuuummm... 1st train for sprints, then work your way up from there.

As for your knee, I would really suggest you seeing a Dr. and making sure it's OK to start a full on training plan. Just a check out before starting down this crazy road, wouldn't help.

After the Dr. make sure you get some GOOD SHOES that are made for your stride/form/strike. Good running shoes are worth the money and money saved on Dr. bills because of injury.

Finally... I will tell you... you can do it. GOOD LUCK!!!!