how to access child element in css code example

Example 1: child css

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

Example 2: css child selector

/*
	Descendant selectors are used to match to any nested element. 
	Child combinators, on the other hand, only match to the direct 
	child element and are defined by the greater than symbol. 
	The selector on the right must be the direct child of the element 
	on the left.
*/
/* child combinator */ 
  parent > child {...}

/* descendant selector */ 
  parent child {...}
  ancestor descendant {...}