The Hansons method linked to by GTF is a great place to start. Another of my favorites, though one that makes you do a little more work in planning, is: http://www.fitnesssports.com/lyd_clinic_guide/Arthur_Lydiard.htm
Even with that 16 week plan, the thing to remember is that it probably assumes you've already done the work to establish a base of aerobic fitness. That's what your next 3-4 months should be about. Answers to the questions Ed asked might give a good idea of where you starting point is and what might be called for next, though most of the advice would boil down to gradually building up from where you are at now as your body allows.