Welcome to the forum.
Try not to think of it so much as going on a diet - but more an idea of adopting a new lifestyle that you keep up forever... The problem with diets is that people think of doing them for x days or weeks... they go through hell for those days or weeks sure in the knowledge that they could never keep it up long term... they count the days until the end or abandon it before the end... The problem is that they are delighted when it all ends and often then start to gain weight again...
The trick is to build really healthy new habits that are really not nearly as bad as all those cruel diets...
Become more active... This does not mean that you have to be a contender for the Olympics... you can start off by doing what I did and going out for a walk every day... I am actually a firm believer that we would all benefit if we wore a pedometer and wore it all the time and allowed it to challenge us to walk more steps in our day... A lot of experts say that we would all be healthier if we walked at least 10,000 steps every day... That may sound a lot - but it isnt nearly as hard as it sounds... All it really takes is a desire to get healthier and the willingness to put in some effort to make it happen.
Eat healthily at the appropriate calorie level for weight control... Now this is not going to happen overnight - but great first steps are to try to eat as little junk food as possible, drink 1 ounce of water for every 2 pounds that you weigh and eat 5-a-day i.e. five portions of fruit / veg every day. There are more healthy eating things that we are better off if we try to do them - but we do not have to start everything on day 1... Try to build those good habits and it will be a great start.
As for your problems retaining your focus... I honestly think that you would find things easier if you made friends that were trying to also lose weight - either here or in real life... There are certainly plenty of friendly people here that you could support and would maybe support you.
Other ways of making friends in the same boat would be by for instance joining a slimming club or joining a gym and making friends with some of the people there... You may fancy going to an exercise class and seeing whether any nice people also go there...
I suggest that you read the following thread - it may help you settle in and make friends here
http://weight-loss.fitness.com/threads/57955-My-advice-to-newcomers
Good luck with your project.