Buy good quality running shoes. Change yor diet to carb and protein. Just run at a pace that you can handle to get as far as you can before you need to stop for a walk. Power walk when walking. Start with 5 k but you will most Likly run only 2k per time then walk 500m run the rest. Stretch before and after and only go running every 3rd or 2nd day until you build your strength. Don't push your self. If you are too sore have a few extra days off. Don't rush to be the best right away. Running as quick as you can even if its a slow as power walking, your are still running to your current ability.