The old addage "It's simple you have to burn more calories than eat" is fundamentally true but it's way too simplistic.
I don't know how much weight you have to lose whether it's a lot or a little in certain places - but lets assume you have a lot because you're male and men tend only to want to lose weight when it's really starting to be a problem.
Why do you eat?
Some people have appetite problems. No matter how much they eat they are ravenously hungry all the time. (I actually know someone with the opposite problem too).
Do you snack outside of meals due to boredom?
Perhaps you eat too much at meals?
Are you a big drinker, there's a fierce load of calories in alcohol.
Lazy gun's diary is a good idea. Try it for a week, no dieting, that's cheating. Don't count the calories at the time, just what you eat and drink. Weigh the food wherever possible. Don't forget to count the booze!
Then at the end of week add it up
You should be taking in something like this:
http://www.csgnetwork.com/caloriesmalecalc.html
Prob about 3,000 calories
You should be able to see where most of the excess is going.
Now the difficult bit. You have to change for good. Crash dieting will just come back on again quickly you have to change your lifestyle and let it come off.
Try to be really strict about not snacking, keep fruit about for emergencies. Foods that make you feel full are really good - There are some good fruit muselis that I like, they are actually quite a lot of calories but you don't feel like eating again for hours.
Don't join a gym unless you really can keep it up. Group sports are best it's less easy to drop out when people ae expecting yo