Making up your mind to lose the weight is the most important part! Eat good food,meaning healthy food.Lean meats,lots of vegetables and fruits,lots of water.Eliminate soft drinks like soda and fruit juices.Drink water or tea.Watch the dressings and sauces,lots of sneaky calories in those condiments.
Any exercise plan needs a good balance of aerobic/cardio and anerobic/resistance exercise.Start off easy do some push ups and sit ups,the amount you do and the number of sets really depends upon your condition.Walking is a good way to start off until you can jog and then run.Work your way in to these things.
Get a physical if you havn't in a while so you get the go ahead to embark on a diet and exercise program.
Here is a list of web sites that I find very helpful.Rosstraining,Crossfit,Bodyweight Culture,John Berardi nutrition,Clarence Bass Ripped.Read the articles on these sites,go to their forums,there is a ton of excellent information.
I wish you good luck!