how to set nthchild in p tag code example

Example 1: nth-child() css

/* Selects the second <li> element in a list */
li:nth-child(2) { 
  color: lime;
}

/* Selects every fourth element
   among any group of siblings */
:nth-child(4n) {
  color: lime;
}

Example 2: child css

p:nth-child(2)
 	{     
 		background: red;
 	}