Advise for newbies!

Take it slow. This is a marathon, not a sprint. At 6'6" your ideal weight, you're shooting for 193-235lbs according to https://www.pinterest.ca/pin/289989663478713844/. With over 75lbs to lose, you CAN set MFP for 2lbs per week loss initially, but you don't have to. As you shrink, so will your calorie needs, so even if MFP gives you a number you think must be too generous, don't worry. You will lose.

For me personally, at a good deal shorter than you, but starting with nearly as much to lose (woman 5'3", starting weight 254lbs with healthy weight range 108-140), I set for 1lb per week and found it much easier to stay on track without feeling hungry or deprived.

Get a food scale and weigh your food. Measuring cups and spoons aren't nearly as accurate and as your weight comes down, accuracy becomes more important.

For weight loss, calories are king. You could eat nothing but snack cakes and, so long as you're in a calorie deficit, your weight will drop. But you're likely to be hungrier, more miserable, and less healthy as you do. The thing is? If you ate nothing but kale, you'd have the same problem. Fortunately, most of us eat a variety of foods and get our nutrition that way. My point is, losing weight doesn't mean you have to give up the foods you love. It means that you might not be able to eat everything you want as often as you want to or have as much of them as you used to. And over time, you may find you're making other choices, not because you CAN'T have X, but because X no longer feels worth the calories. (I find I no longer have room for 600-calorie apple turnovers, nor for the 300 for half a turnover. A quarter of one isn't worth it anymore. On the other hand, I just baked a batch of super-rich vanilla cookies. Each one is 90 calories. They're absolutely delicious, but I'm now at a point where I can have one or two and then stop. It's not that I've given up dessert; it's that for the calories, I'd rather have 2 cookies than a quarter of a turnover.)

Don't get discouraged if your weight loss stalls. Water weight happens. Hormone fluctuations happen. Annoyingly, if you start a new exercise program, you may find a temporary weight uptick—water weight again. It passes.

You can lose weight without exercise, but exercise has other benefits. Not the least of which is more calories to play with. Plan on eating back a portion of your exercise calories; you've already got a deficit built into the goal MFP sets for you. If you make that deficit too large (by exercising and underfueling), you could be setting yourself up for lethargy, weakness, hair loss, brittle nails, increased hunger... plus, if you run too aggressive a deficit, there's only so much fat your body can burn in a day. Then it starts in on muscle. Your heart is a muscle. Eat back at least half your exercise calories. If MFP was 100% accurate, you'd be better off eating them all, but it can miscalculate exercise burns. There are incorrect food entries in the database. You're not going to get all the data exact, but you can at least be in the right ballpark.

Read the stickied posts at the top of each forum. Lots of good info in them.

And relax. You can absolutely do this.