Here: this recipe from Mario Batali is just great and not very difficult. Simple ingredients, not expensive and really good with freshly grated pecorino romano cheese. Takes about an hour from start to finish.
http://www.seriouseats.com/recipes/2007/10/mario-batali-recipe-for-marinara-sauce.html6 tablespoons virgin olive oil (basically a quarter cup and use a heavy big pan/like sautee pan/frying pan w/thick bottom to distribute the heat evenly)
1 Spanish onion, cut into 1/4-inch dice (use a biggish one or two medium onions)
4 cloves garlic, thinly sliced (I use 6+)
4 teaspoons fresh thyme leaves (or 1 teaspoon dried) (You should invest in one of these plants. They can be grown in a pot easily, or just buy the fresh herb at the grocers)
1/2 medium carrot, finely shredded (we use a whole carrot and grate it with a standing grater/if the tomatoes are really acidic you might want to add two medium carrots as they help sweeten the sauce)
2 28-ounce cans of tomatoes, crushed by hand and mixed well with their juices
Salt, to taste
(we add a couple sprinkles of red pepper flakes)
Procedures
1
Place oil into a sauce pan with onions and garlic, and cook over medium heat until translucent but not brown (about 10 minutes). Add the thyme and carrot; cook 5 minutes more. Add the tomatoes. Bring to a boil and then lower the heat to just bubbling, stirring occasionally for 30 minutes. (We usually let it cook for more like 45).
2
Season with salt to taste. Serve immediately or set aside for further use. The sauce may be refrigerated for up to 1 week or frozen for up to 6 months.
(Taste it part way through and if it seems a little too acidic, add a small teaspoon of sugar.)
This sauce freezes well, so you can make a batch for a couple meals and freeze the leftovers in plastic containers for later. It thaws and reheats quickly.