Ok, I will keep this simple....
Ok, I will put something up here just in case someone really needs simple direction oh how to change your oil. The first thing you want to keep in mind is never do this after the car has been running because that oil will be VERY hot. So only perform this after the engine has had sufficient time to cool down. You will need a drain pan to collect the used oil, an oil filter wrench, sockets and some paper towels.
Changing the Oil
Now depending on what engine you have in the car, the oil filter and drain plug might be in slightly different locations, but they are generally located under and on the side of the engine. The photo above is from a Pontiac 400 engine. You need to jack up an support your car on Jackstands or ramps or whatever you have to make sure your car is stable and safe. Slide under the car and position your drain pan under the oil drain plug and remove the plug. Once the oil has stopped draining, move the pan over under the oil filter and remove the oil filter and let that oil drain. Install the new oil filter and use a little bit of fresh oil around the seal on the filter. Re-install the oil drain plug and fill oil to capacity using your owners manual for the recommended oil viscosity and amount. For example, the Pontiac 400 is 6 quarts of oil when changing the oil and filter or 5 quarts if not changing the filter. The Olds 403 is 5 quarts of oil when changing the oil and filter or 4 quarts if not changing the filter. Refer to your owners manual for the proper amounts.
Once you have refilled the oil (making sure there are no leaks underneath and the oil filter and drain plug are properly installed and tight), start the engine and let it run for about 30 seconds and then shut it back off again. Check the oil level to ensure proper levels on the oil dipstick. And then you are done, check for leaks again and drop the car off the stands.