Dola, That link to FIRST's marathon training plan is probably not really relevant for you.. here is a better one for you, a link to their 5k training plan:
http://www2.furman.edu/sites/first/D...ram-metric.pdf
It has 3 exercises a week, Intervals, tempo Run, long run. The long runs never get beyond 12k (roughly 7.something miles) which seems to be what you indicate you want. Give it a look