oil leak???

here goes the book,i have a 87 b22 and right behind the valve cover head area there is a pin hole tht spurts oil.its actually in a recessed circle about the size of the bottom of a coke can.and on my junk mazda it appears to be a plug or cap that goes there.but i have no clue so anyone can help me at all i would appreciate it so much..i miss drivin my truck..sorry for the book.