Before you learn anything fancy about cooking you have to learn how to KISS. Before we get overly excited here, you should know that KISS is an acronym for "Keep It Simple Stupid."
1. Selecting the steak: You really have to learn livestock anatomy here. This is not difficult, livestock anatomy is pretty much the same across the board. For example, a Porterhouse steak is the same cut as a center cut loin pork chop. If you are in a hurry, you can always make a friends with the butchers at your local supermarket. They will be happy to discuss your needs and cut you something special if you request them to do so.
2. Let's assume you found a Porterhouse steak on sale: There are many ways of cooking it, but let's keep it simple for now. Marinade? Forget about it! The best cuts do not need it and will suffer from it. I think grilling or broiling is best when you are cooking meat of this quality. Seasoning? Keep to salt and pepper for now, there is no need to guild the Lilly.
Pepper the steak lightly and do not salt as it only draws out moisture. Add salt to taste after the steak is cooked. If you are cooking outside on a grill keep the steak 2 inches above the heat source, cook about 7 minutes per side. Use the same formula for cooking inside under the broiler on your oven. This method should cook the steak to about 145 degrees, which was the old standard for medium rare. The new standard is 165 but that is really over kill with beef.
3. So the steak is done what next? It isn't really what's next. You should plan ahead what you want with your steak and had it cooking while the steak was cooking. Again, keep it simple.
4. An example: Tonight I am having a 2 inch boneless Rib Eye steak, that I will cook in the oven on broil 2 inches from the heat source. I am making a side of butter sauteed sliced mushrooms with a splash of brandy for flavor. The mushrooms with brandy will be served over the steak and over the mashed potatoes I am making as well. As the steak is thick I figure 10 minutes per side for this one.
5. Read cook books. You will learn. I suggest you start reading with James Beard who really knew how to make great food simple