Get a healthy diet chart by using this link: http://www.healthcaremagic.com/diet-plans-from-nutritionist.
Next start running, cycling or swimming. Join a gym. Use public transport so that you get to walk more, ditch the elevator & use the stairs.
For more check out: http://www.healthcaremagic.com/articles/Exercises-to-lose-weight/7163
http://www.healthcaremagic.com/articles/Tips-for-weight-loss/200