What kind of car do you have? From the under-hood pics, it looks like an Accent? Just make sure the gasket is for your year and model of car. No extra sealant is needed with the gasket. Be sure to tighten the bolts in the proper order and to the proper torque. And be sure to re-check/re-tighten the valve cover bolts after a couple of days of driving.
Former Hyundai owner, still here to help.
2011 Honda CRV (family mover)
1991 Isuzu Impulse RS
1991 Isuzu Impulse RS (parts car)
1993 Asuna Sunfire (parts car / stripped)
2007 Ford E-250 (work truck)