I'm assuming you have a socket set? It's easiest to do when the car is slightly warm, but it needs to have been sitting for a good hour before you change it so all the oil has a chance to make it back to the pan. Make sure you have a spare crush washer too.
1. Put some blocks in front of/behind at least one rear wheel. Put the parking brake on and put it in gear.
2. Jack up the front of the car and put it on jack stands. If you don't have jack stands, you should buy some. Either that or use two jacks on the same side right next to each other, one jack as the primary and one as the safety.
3. Remove the plastic plate underneath the front. It's attached by several 10 mm screws and several click-in pins that you just pull out.
4. Remove the oil filter and put it on top of your drain pan to drain.
5. Remove the oil drain plug.
6. Get out from under the car and remove the oil filler cap. This lets the oil drain more easily since air can get into the system from the top.
7. Give it a good 20 minutes to drain, or until the oil coming out of the drain hole is dripping at least 20 seconds apart.
8. Replace the drain plug using the new crush washer.
9. Replace the oil filter. I always rub a tiny bit of oil on the rubber gasket to make it easier to tighten it by hand and ensure the gasket seats perfectly on the flange.
10. Replace the plastic shield.
11. Lower the car off the jacks / jack stands.
12. Fill up the car with 5 quarts of synthetic 5w-30.