If you need to ask then pay someone to do it before you cause £100s of damage to the wiring looms. When I used to do auto electrics I’ve seen some right gash jobs, some of which have resulted in large portions of the car’s wiring loom being melted to the point the only solution was to replace it which often means hours of labour just taking stuff out of the vehicle, such as the dashboard, so you can get to it all.