http://www.bbc.co.uk/food/get_cooking/cooks_guide/
This website tells you how to cook most things and gives you tips on choosing the foods, methods of cooking and so on.
It's a pretty much a basic guide to cooking different foods.
The more and more confident you get with cooking the better you get at it. You're not going to be serving a perfect meal on the first try, you'll learn from mistakes.
As far as looking for what "goes" with what, search for some basic recipes. Say you have Salmon... search for Salmon Recipes. A good healthy meal (in my opinion) is a lean protein source, like Fish, Chicken etc, served with some potatoes and vegetables.
If you're looking for tasty recipes that are also healthy and ideal for an athlete, try looking in the book "Muscle Chow":
http://www.amazon.com/Mens-Health-Mu...2507004&sr=1-1
As far as what's healthy... avoid stuff from packets as often as possible.
What you want to eat is vegetables, berries, fruits, nuts, seeds, lean meats, beef, pork, fish, dairy, eggs, bread, pasta, oats and so on. You get the idea, good wholesome food. Get it locally sourced if you can, the less you buy from supermarkets the better. Free range eggs for example or raw milk is superior to what is sold in the supermarkets.
Some people like to eat a little lower carb, but personally I know plenty of healthy folk who eat a good amount of carbohydrates. Stick to good wholesome food, like I listed above, of course I will have missed something out, but you get the idea. Stay away from junk food like chocolate, potato chips (crisps), pizza and all that kind of shit. Do not avoid fat. Dietary fat will not make you fat. Make sure you DO get plenty of healthy fats. Search healthy fats on google for an idea of what I'm talking about.
The problem with a lot of food is the added shit they put in it. So this is why it's healthier to stick to locally sourced food.
For more on healthy eating, or what we deem to be healthy:
http://www.westonaprice.org/
It's a brilliant site on one of the few nutrition resources I trust.
I recommend this book for nutritional guidelines, by Weston A Price:
http://www.amazon.com/Nutrition-Phys.../dp/0879838167