Here's how we make ours.
You will want to prepare all your ingredients ahead of time because once you start cooking it goes pretty fast.
First cut up some onion slices, and mince a few garlic cloves. Pour a couple of tablespoons of oil in your wok (or frying pan). Turn your heat on high, and once hot throw in your onions and garlic. The amount of garlic and onions is really to your taste, but I recommend not skipping this step because they really add flavor to your dish. Saute until onions are clear.
Next put in your meat. Chicken, beef or tofu all work well. Your local grocery store even sells beef precut for stir fry if you're really short on time. Make sure your meat is cut into about square inch pieces. Cook until meat is done, constantly stirring. One of the tricks to stir fry is to continually mix it to evenly cook it and to keep it from burning.
The next step is to add vegetables. We usually buy a premade bag of stir fry vegetables to save on time, but you can choose any veggies that you prefer. 
In addition to the premade bag, we also add bell pepper slices. One thing to note is that you add veggies in the order of longest cooking time. Broccoli and carrots go in first, bell peppers go in last. You want all your vegetables to stay crispy, so you only want to cook them a little while.
We also like to add noodles. The brand we buy is pictured below, but we just use the noodles and throw away the spice packet that comes with it. These are prepared by poking holes in the plastic they come in inside and microwaving for one minute. Then add them to your wok. If you rather, skip the noodles and serve your dish over rice.
Add about a quarter cup of water and add your stir fry sauce. I'm sure there are some great recipes out there to make yourself but our favorite is House of Tsang. (Remember this is a quick meal, making sauce from scratch adds time). Their classic is good, but if you like spicy try the Szechuan sauce. Add to taste, I think we usually use about a quarter of a bottle.
Mix until sauce is hot and food is coated. Serve immediately.
And that's it! Just 15 minutes to make a quick satisfying meal!