It's very easy to bake a chicken breast. Prepare your breast for cooking. I trim off any fat, skin and bits of bone and then rinse it briefly under cold water and pat dry with a paper towel. I generally also marinate my chicken breasts because otherwise they can be a bit flavorless. Preheat your oven to 375 degrees. When the oven is ready take a baking dish or pan, hit it with some non-stick cooking spray, put your chicken breast in it and place in the oven on a rack in the middle. Wait 20-30 minutes. To check to see if the breast is done, take out of the oven and cut into the thickest part of the breast. If the juice runs clear the breast is done. If the juice isn't clear, place it back in the oven and give it a little more time.
Because chicken can be a carrier for salmonella I like to be sure the breast is done and use a meat thermometer instead of the juice test. There's some dispute over at what point it's safe to eat a chicken breast but everyone I've read seems to agree that by the time the thickest part of the breast reaches 170 degrees Fahrenheit any bacteria should be dead so that's the target I use.