There really are no precise proportions needed here. If I am canning the apple sauce and want to make sure they have enough acid, I usually add about a teaspoon of lemon juice per quart. More detailed instructions for canning are here (although they do not add lemon juice). I don't add sugar because I find that the apple sauce is sweet enough as is, but a pear or two thrown into the mix is delicious.
a mix of varieties of sweet apples, washed, cut into quarters, and cored (peels still on)
1 or more cinnamon sticks
Put the apples and cinnamon stick(s) in a large heavy stock pot. Add a splash of water to keep the apples from burning before they release their own liquid. Cover the pot and bring the apples to a simmer over medium-low heat.
When they are very soft, but while they are still hot, scoop them out with a slotted spoon and run them through a food processor. It is important to do this while the apples are still very hot because it will give them a smoother consistency. Purée until smooth.
If you have apple juice left over, you can add it to the sauce for a thinner consistency, or drink it. Serve the apple sauce warm, at room temperature, or chilled. Warm apple sauce is especially tasty over vanilla ice cream or with gingersnaps.