This is probably not very authentic, but it is a good recipe. It is so old, it actually calls for a 2 lb 3 ounce can of tomatoes, which haven't been around for a long time. Taste toward the end of the simmering time and adjust the oregano, basil and salt to your taste.

About the sugar, if you slowly cook the onions until they are soft, they will sweeten the sauce and you will not need much sugar. Also depends on the brand tomatoes you use. Italian brands are sweeter. If you can get them, they are wonderful. I understand Italians never put sugar in their sauce. You might want to hold the sugar until it has simmered for a half hour or so, then taste.
I also add a pinch of cloves and some red pepper flakes to my sauce. Sorry to not be more precise, it has just sort of changed and evolved over the years.

I make meatballs for it, but it is good just as it is.

Spaghetti Sauce

1/4 cup olive oil
1 cup chopped onion
1 or 2 cloves garlic, crushed
1 28 ounce can tomatoes, including juice (cut the tomatoes into pieces)
2 6 ounce cans tomato paste
1/2 cup water
1/4 teaspoon dried oregano leaves
1 teaspoon salt
1/8 teaspoon pepper
2 tablespoons sugar
2 tablespoons chopped parsley

In hot oil in dutch oven, saute onion over medium heat 6-10 minutes, stirring often. Don't let it get brown, just golden. Add garlic during last couple of minutes.

Add remaining ingredients and mixwell. Bring to boiling, stirring. Reduce heat; simmer, partially covered, 1 1/2 hours. Stir occasionally.

Note: If you are having a red wine wine with your pasta, you can stir 2-4 tablespoons of it into the sauce along with the other ingredients.