I received a request from a reader for a recipe for homemade ketchup. To truly make ketchup from scratch, a person would have to grow their own tomatoes, cut them into little pieces, boil them down, run the juice through a sieve, and then add the rest of the ingredients.
However, I place that right along spinning your own wool, or making your own soap. If you have the inclination, great. Most of us just don't want to go that far. She forgot lentil weaving and knitting your own yoghurt. 
It is much easier to start out with some tomato paste, thin it slightly with water and add the sugar, and spices.
Here are the basics:
1 Can Tomato Paste
1/4 Cup Water
1/4 Cup Brown Sugar
1/2 teaspoon salt
1/4 teaspoon Cumin
1/4 teaspoon dry mustard
1/4 teaspoon cinnamon
1/8 teaspoon cloves
2 Tablespoons Cider Vinegar
Mix together, cover and refrigerate. Remember that when you make things from scratch, they don't have as many preservatives (good and bad). You are going to have to use it up in a month or so.