Hi and welcome from me too.
Becoming an active member of this forum was probably the single most helpful thing in my first few months of diagnosis, so hopefully you will find the same.
I came into things slightly differently in that I was initially assumed to be Type 2 so I had 6 weeks of very strict diet and oral meds before being started on insulin, so I was very aware of the effects of carbohydrates before I started injecting insulin and had got my readings down into single figures by gradually cutting out almost all carbs from my diet and using my BG meter to see which foods caused me the most problems and then simply avoided them. I now continue to eat low carb which means I need to inject less insulin.
As
@Kaylz says, the starting point is generally 10g carbs to 1 unit of insulin and then see how you go. The more often you test, the more you will understand how your BG responds, so be prepared to experiment and test lots. Before eating and 2 hours after is a good starting point.
Details of the carbohydrate content of foods is found with the nutritional information on packaging, usually in small print on the back or side. Total carbohydrates are what you are looking for. Ignore the sugar content.
So things like porridge oats are usually about 63g carbs per 100g, which means that a 50g portion of those porridge oats contains 31.5g carbs (say 30g for round numbers) . If you have sugar on it then you need to weight or measure the sugar. There is about 5g carbs in a teaspoon of sugar, so 3 level teaspoons of sugar would be 15g carbs. If you have a dozen large blueberries in it you can probably add another 10g carbs, so that would add up to 55g carbs... add in your milk and some milk in your coffee and you are up to 60g so if you assume 10g carbs to each unit of insulin, your 6 units of NovoRapid for breakfast would be near enough right if that was the breakfast you ate.... I am just giving it as an example though. If you replaced the sugar with sweetener and didn't have the blueberries you would be looking at about 35g carbs with the milk which would be equivalent to 3.5units of NR. Assuming you don't have a half unit pen, you would then look at your morning reading and if it was a bit high you would round it up to 4 and if it was a bit low you would just inject 3 units. Then you test 2 hours later and record the reading and then before lunch. Keeping a food diary with your readings is the single most useful thing you can do and there are phone apps you can download which you can use for this. MySugr is one such app.
If you lunchtime reading is consistently higher or lower than you expect then it suggests that the insulin ratio for the previous meal was incorrect so you might have to adjust the ratio to 15g to 1 unit of insulin if you are particularly sensitive to insulin and your lunchtime readings were consistently low or 5g carbs to 1 unit of insulin and see how that goes, but 10g carbs to 1 unit should be the starting point.
I know it probably all sounds very complicated at first, but it soon becomes second nature and you know the carbohydrate content of a whole range of products off the top of your head and learn to assess the number of carbs reasonably closely just by looking at a plate of food. There is a lot of work involved initially, but it gets so much easier with practice.
As others have said, anything you don't understand, just ask. If you want someone to double check your calculations for the carb content of foods until you get the hang of it, I think it would probably be OK for us to do that. What we can't do is tell you to take a particular dose for a particular meal.