5k run training

the biggest mistake that most beginners make is that they start off too strong and cant finish. you want to start are slow and work your way up. you want to start training with intervals of run:walk. your first run only has to be 14mins long with 30second runs followed by a 1min walk. you want to slowly add more time to your run and less from your walk, 30 seconds at a time. your walking period should only last between 30second and 1minute. go out at least three times a week.
When I teach learn-to-run here is the generic run to walk ration I use. if you find the run to be too easy add 30seconds-1minute, just make sure your able to sustain your pace for the remainder of your run.
Wk 1- .5:1 (30 second run: 1 minute walk)
Wk 2- 1:1
Wk 3- 1.50:1
Wk 4- 2:1
Wk 5- 2: .50
Wk 6- 3:1
Wk 7- 3: .5
Wk 8- 3+:1
For easier breathing take deep breathes in through your nose and out through your mouth, and make sure your standing up straight. If you get light headed or short of breath, walk slowly with your arms up, do not suddenly stop. make sure you stretch afterwards so your able to get back out there tomorrow! With determination, I guarantee you will be able to finish a 5km run in 8wks! good luck!!

http://www.c25k.com/

its a 9 week program, but I'm sure you can fit it into 8 weeks.