The sump plug is located on the base of the engine, and is accessed underneath the car
Do not forget to have a suitably sized receiving tray in place
Using a 22mm spanner or socket, carefully remove the sump plug and fully drain the oil. When the sump has emptied, wipe clean the sump plug area with a paper towel and refit the sump plug and washer
Replace (new) sump plug and washer. Do not overtighten