The oil filter is located on the side of the engine under the ignition wires. The filter cartridge is unscrewed using a special wrench, which can be purchased at auto parts stores. If there is no such key and you need to replace the filter, you can insert a screwdriver into the filter from the side and unscrew the filter using the handle of the screwdriver.
After unscrewing the filter, clean the seating area on the block and lubricate the gasket of the new filter with engine oil. Screw the new filter until the gasket is in contact and from this position tighten the filter another 3/4 turn. Do not use any tool while doing this. Turn on the engine and let it run for a while. Check for oil leaks at the filter connection. Check the engine oil level and add oil if necessary.