Nutrition facts on BigOven are determined from the ingredients. Each ingredient line is linked up to a corresponding item in the nutrition database.
If you are a basic (free) member, you can change the serving size of the recipe, which is used in the "calories per serving" calculation. Make sure that the serving size is accurate for the recipe. To change it, see "How do I edit a recipe I've Posted or RecipeScanned".
For line-by-line nutrition, if you're a BigOven Pro member, you can simply click on one of the bullets in the recipe itself to link a recipe to its nutritional equivalent. For instance, clicking on one of the red dots in an ingredient listing (when you are logged in as a Pro member) will bring you to a nutrition linking screen.
Let's click on the "Ground cinnamon" bullet:
We see a screen that shows this. BigOven knows that "Ground cinnamon" corresponds to "Spices, cinnamon, ground", and it needs to know how many grams are in 2 tsp. All you need to do is click on the "1 tsp" line and put a "2" in the multiplier box, as follows:
That's it! Just click Done, and BigOven adds this nutrition information for cinnamon into the recipe as a whole.