I also, am a computer engineer and am tied to a computer all day. I started at 185lbs and 20% body fat. Not nearly as big as you proclaim yourself to be, but in a similar position nonetheless.
Diet is very important: I use a protocol called Intermittent Fasting. If you can embrace this lifestyle change you will drop fat very fast. Get in a caloric deficit, eat healthy foods, and stay away from fast and fried foods. MyFitnessPal, as mentioned in other answers, is a big help for tracking calories and macronutrients, add this in with IF. Supplement with protein shakes, etc.
Exercise: Unless your arms don't work, stay away from elliptical machines, and the treadmill to start. Get on a workout routine where you strength train maybe 4 days a week and do some kind of low intensity cardio, i.e brisk walks (1 hour), until you can get into some HIIT High intensity interval training.
Make your strength training a split routine, try Chest/back, arms, legs, shoulders - do not run around the gym and try every machine there is to get a full body workout. It's not going to do anything dramatic, compound movements are your friend, try to squat, bench, deadlift, etc. I used the Get Swole program, which worked very well for me. (Nevermind the stack of musclepharm products, and the meal timing they are irrelevant)
Core Development is hugely important and has been a major factor in my progress. Make sure to spend some time and do core work, maybe on your low intensity days. And I don't mean crunches I mean planks, weighted twists, resistance twists, ab rollouts (if you can), etc.
Take your time: It's going to take a lot of consistency in your diet, don't get misguided. If you fall off track: get back on.
Also in terms of timing, I wake up eat 5:00am and get to the gym by 6:30-7:30 before I start my day. That, intermittent fasting and bulletproof coffee result in high energy, high focus, excellent fat loss results, retain lean muscle mass, and see results, which is of course the most important thing.