Whenever I'm looking to make something I've never tried, I seek out recipes from a site that has reviews. I look for something that has many good reviews (not just 5 stars from one person). Then be sure to read the reviews, as they often have good suggestions and details on how the recipe worked for them.
For example, here's a tomato sauce recipe from Allrecipes.com. Seems pretty straight forward: smush up the tomatoes, throw them in a pot with oil and spices, cook until done.
Based on your description, I'd guess you're either cooking at too high a heat, cooking too long, not using enough tomato, or not using enough oil. Very hard to tell without knowing more about your process.
As for a simple method to generate sauce from tomatoes: I generally don't make that rich, heavy sauce one typically associates with Italian tomato sauces. I make a fresher, lighter sauce that goes something like:
- Start some pasta cooking in well-salted boiling water.
- Heat a few tablespoons of olive oil in a fry pan over medium-low heat. I generally use decent extra-virgin here, as I won't be sauteing or frying in it.
- Dice some onion and add to the pan to sweat them down a bit. They should gently sizzle, not hiss and pop. If they do, turn the heat down.
- Mince some garlic, add to the pan. Just cook for a minute or two to flavor the oil.
- Dice the tomatoes and add to the pan. I normally dice them whole, skin on, and leave most of the pulp, juice and seeds.
- Add a pinch of salt, some pepper and a small pinch of red pepper flakes (a larger pinch if my wife isn't joining me).
- Cook until the tomatoes cook down and the sauce looks yummy.
- Chiffonade some fresh herbs (I love fresh basil and oregano, and roll up all the small herbs in the big basil leaves to make everything easier to thinly slice) or add a pinch of dried. I like to wait until the end to keep the herbs tasting bright and fresh.
- Drain the pasta, reserving some of the cooking water.
- Drop the pasta into the fry pan and toss with the sauce, adding a bit of the reserved pasta water (see here for some reasons why).
- Toss and cook for a minute or two to get the sauce and pasta loving each other thoroughly.
- Taste, adjust seasoning to your taste.
- Enjoy with a nice Chianti.
I know that looks like a lot of steps, but it's actually super-simple, and breaking it down into print is way more complicated than actually making it.