5 pounds of tomatoes makes about 4 quarts of tomato purée with a couple inches of headspace for freezing
Stem tomatoes as you chop them, quartered or so for big ones, cherries cut in half. Add them to a large pot.
Bring to boil on the stovetop, lower heat and simmer 10 minutes. Remove from heat and let cool before passing all through a food mill or chinois. Use a ladle and canning funnel to transfer into storage containers, quart jars are ideal.
This tomato purée will keep well for several days, refrigerated, so do that if you will have time to make tomato soup in the near future. Otherwise, transfer to sterile jars (boil for 10 minutes) or freezer bags, cool completely, label and freeze for 6 months to 1 year.
Use for making tomato soup (which doesn't take long) or tomato conserve ( when you have a few hours to be around the kitchen).