Yes everything has been said already like spot reduction being BS and sit-ups not getting rid of fat. Situps are mostly done wrong anyways, you only do 1/4 of the movement to work the abs otherwise you are working different muscles altogether and better exercises exist than the situp for the abs.
I would suggest you start a diet now. Look into Tom Venuto or Chris Aceto even Craig Balantyne as they are great coaches on fat loss plus they know about packing on mass to get that cut look.
Once the diet is sorted out you can than train. Simply put just burn more than you consume and you will lose fat but also makesure you consume extra aminos, vitamins, minerals and protein because you will start to lose muscle otherwise aswell with the fat which you dont really want but will lose alittle muscle anyway, its one of those things when you go on a diet that you will lose some muscle as its unavoidable but you can limit it with a careful addition to the diet.
For exercise you can do the things as mentioned like Girth Hammer says those compound movements will burn shit loads of energy off so things like deadlifts, squats, dips etc will help you and you need not that many. If you need help makeing a routine let me know and I will do one for you.
Add in jogging or brisk walking daily like X3 times as they are GREAT for fat burning with brisk walking being one of the best, better than swimming. You could also incl rowing but it can be VERY gruelling to the system and if fat loss is just your aim than it isnt needed but if you want to really improve cardio endurance and longetivity than it is something to consider.
Buy yourself a skipping rope aswell that is a great simple cardio workout and if you dont like going out around town because of gangs and other shit heads that are about these days than grab yourself a barbell which is heavy, like a 7ft Olympic one or standard one which are approx 10lbs or so in
weight, probably less and get into the sqiat position with NO
WEIGHT added and do squats non-stop for 20-30 or more minutes.
That is a fucking intense cardio workout my freind and one the British military use in combat zones when they cannot get to the gym, it works to keep them fit. You need no
weight as your movement useing all your body is burning tons of energy off ... great simple little trick.
Lots of water drink too mate on the diet. The big think to remember is cutting CARBS as apposed to FAT because fat actually burns fat ... the carbs are the nasties sometimes when you are wanting to lose
weight and after your intense cardio sessions do consume your protein shake and other stuff you may add to it because your body will enter a catabolic period especially when cardio is done, which is good for fat loss but it also is very lethal to burning the muslce tissue you have so to limit that you must consume protein and other things such as amino acids to limit the damage.