Hi,
Sorry to hear you're struggling so much, it's horrible being diagnosed with diabetes.
Controlling diabetes is a bit of a big subject, but the basics come down to the fact that insulin lowers your blood glucose, and eating carbohydrate raises it (starches like bread, rice, pasta and potatoes raise it just as much as sugar does). If your bloods are permanently high, it implies that you're not injecting enough insulin to cover the amount of carbohydrate you're eating.
It's not just as simple as injecting more insulin willy nilly though; you do need to know what you're doing, how much to inject and when. If you're not comfortable adjusting your insulin doses to match your food, I would suggest speaking to your diabetic team for help. Being able to adapt your doses properly is really important in getting good control, but you do need to learn how to do it - it's not hard, but it's also not something I'd like to try simply explaining on the internet either - too much room for error!
Food choices are also not that simple. Many people find that eating less carbohydrate gives them their best control, BUT again you need to balance the insulin to the carbohydrate; if you were to simply eat less carbs and keep the injections the same you might set yourself up for hypos. Again, this is why it's important to understand how it all works, and speaking to your diabetic team about all of this is your best bet in my opinion.
Do read up as much as you can on here, on other sites, and in books ("Think Like a Pancreas" and "Dr. Bernstein's Diabetes Solution" are two I'd recommend, both available from Amazon") and learn as much as you can about the condition. Try not to be too disheartened about your current bloods; you're right, they do need to come down, but the important thing is that you've recognised that and you're doing something about it.