Carbs and Cals is an excellent book and app. Available from Amazon and not expensive. I have no problem with the book. I don't need to take it shopping with me!
It shows thousands of different foods in colour photos served up on a plate. It gives the weight, amount of carbs, calories, fats, protein and fibre. It was my bible when I first started and I still use it now after over 3 years.
You can also use the nutrition labels on packaged foods and look for "total carbs" per 100g. You can ignore the "of which sugars" as they are included in the total. Then use your common sense as to how much of that packet/tin/jar you are going to eat at one go and calculate how many carbs that will come to. As the amount per 100g is actually the percentage, this makes it easy. 10g per 100g is 10%, so 10% of your portion is carbs.
You can also use supermarket websites, manufacturer's websites, growers websites. Doctor Google will find these for you. The major supermarket websites now show all their products with all the ingredients and nutrients detailed, including carb content.