Hi there,
Nobody knows what they're doing at first. The diary is an excellent start, as is trying to identify and adjust or eliminate foods and meals that are very high in carbohydrates as a starting point. If you could stand to lose some weight, which may be of great help in controlling your diabetes if you could, then tracking your food intake and recording both carb and calorie content can be invaluable for identifying where immediate changes big and small can make a difference.
If you're comfortable with technology there are apps and gadgets that can make food analysis and tracking much easier. I went for a smart food weighing scale made by a company called Arboleaf, currently £22 on Amazon UK. It comes with an app with no ongoing costs which did everything I needed as regards tracking carbs and calories. It enables you to, for example, see how much carbs and calories are in a specific portion of vegetables, without having to do any maths. To be honest I've only gotten around six weeks of daily use out of it so far, though part of the reason for that is I can now look back using the app at everything I ate for those 6 weeks and look up the numbers, per food portion, per meal, and per day. I'll only need to use it again if I decide to make more big changes to my diet.
However you go about it, information is power! 😉 Very best of luck