run the engine for 5 mins (get the oil warm)
get a oil filter (and oil filter remover tool, of you dont have one), some good 5w 40 oil fully synthitic (halfords have it on offer for £27 for 5ltr, its the own brand but gets good reviews) and a new sump washer (halfords will sell them)
Jack the car up level (secure it on stands)
Remove the plastic plug on the undertray
remove the filler cap on the top of the engine
using a 8mm sump key, remove the sump nut
drain the oil into a bucket, tub etc
remove the oil filter
Re fit the new oil filter with your hands (not using the tool) it needs to be tight but not welded on lol, i always wet the new seal with some of the new oil
re fit the sump nut with the new copper washer
re fit the plastic cap on the undertray
drop the car on a level floor
re fill the oil, allow the oil to settle and re check using the dip untill its almost full.