my friend was hurting for money so i gave him 40 bucks to do a tune up on my car. jus the usual plugs wires oil......i dont think he installed them correctly but i dont remember. Trailing plugs go on top with the blue colored plugs right? so leadings on bottom with the solid black ones?

 

Next to where the plugs screw in there will be an "L1" for leading (1), "L2" for leading (2), (T1), (T2), etc. Hope that answers your question