Closed clubs

Recently someone pointed out to me that I've been hitting all my iron clubs including the wedges with a closed face. No one has ever shown me the correct way to hold an iron exept to make sure that the leading edge was perpendicular to the surface at address. Now this particular person also told me to use a mark etched on the rubber grip of each club and ensuring that the mark was in line with the leading edge when the club was grounded at address. If I do that my wedges would be so open that they feel awkward to hold and hit. In fact I think that has contributed to my slicing my wedge shots or hitting the ball with the side of the club with the ball scooting off to the right (RH Player). Can anyone advise me on how to correct this. I know this sounds basic but please help me out. Appreciate any assistance.

hi niumaiat
this is how i set every clubface square take your club and apply your left hand now place your right hand on the clubshaft below the grip and hold the club out in front of you and turn the shaft until the the leading edge is pointing straight up and so its at 90 degrees to the ground.
then simply apply your right hand grip
your clubface is now square