This is a very quick and simple tutorial on how to look up foods on https://nutritiondata.self.com .
In the upper right, populate the "enter food name" input, and click "Search". In this example, I chose a category, but, that is optional, and sometimes I don't know if something will be listed as a fruit or a vegetable. The advantage of picking a category is that it filters out a lot of crap processed foods you, hopefully, are not eating.
Next you'll see search results. Pick whatever is appropriate.
Now, select your serving size. Since we like to eat 1 cup servings, I'll pick that. Here, it is also useful to see how many grams are in our selection.
Finally, results. I'm just showing the section on carbohydrate. By default you get a lot of information on this page, and you can drill in for more detail, although, it isn't always available.
You can see that a good chunk of your daily allotment of carbs on Level 3 might get chewed up by a cup of strawberries, but, it's not a deal-breaker if you manage the big picture.
Also note that the authors of this site have their own nutritional philosophy which is not entirely in line with the protocol you are following. I've just been using this forever, and I don't know if there are better options.