This is one of my favourite ways to cook chicken. It is a great way, especially if your chicken is a tad freezer-burnt!
Heat up the oil in the frying pan. Cook the chicken on medium heat for about 7 minutes on the first side and 5 on the second. Reduce heat to low-medium (about level 3) and add the salsa to the chicken. Flip the chicken often, and make sure you keep the salsa somewhat touching the chicken so you get the flavour. Basically, you are just warming up the salsa while the chicken finishes up cooking (2 minutes).
This goes really well with a salad on the side.
Note: the cooking instructions are different depending on the thickness of the breast. Your new best thing will become a temperature-checker. The minimum internal temperature of chicken is 74C. You can see the temperature for other meats here.