If you want a large amount of sauce you are going to need 2 to 3 times more (maybe even more) tomatoes then you will think. I am always surprised at how much you think you are going to get and what you really get. Also, I have done my regular sized tomatoes with my cherry tomatoes, and have not had any issue.
First take all your tomatoes and either poke a hole in them or just crush with your hand into a cooking pot. I start my pot with a little garlic, onion and oil. Let this cook down until it looks like this.
Once you have let your tomatoes cook down, strain them into a metal screen colander, over a big bowl. You may have to fill your colander a couple times before you empty your cooking pot. Then take a spoon or pestle and crush your mixture through the screen. This makes removes your seeds and skins. See?
Once I have all my sauce through and have thrown out my seeds and skin, I place it back in my cooking pot, I add my herbs and spices and some store bought tomato paste. The paste helps thicken it up.
The next step depends on how you want to store your sauce. If you have a small batch, you can just put it in a jar and store in the fridge. If you have a lot and want to freeze it, go ahead and place in ziploc bags or an other freezer safe container and freeze. If you want to can your sauce, you will need to place the sauce in jars and boil them for about 30-40 minutes or so.