Define:
First focal point and
Second focal point.

(Please give a definition that fits both lens , i.e., concave and convex )

Dear Student ,
First focal point : The first focal point of any lens is the focal point of the second refracting surface . Second refracting surface means that when the ray enters the lens (whichever side is given ) the first refraction occurs when the ray lies on the first curve and second  refraction occurs at where the ray exits the lens . This second refracting surface's focus is the first focal point .

Second Focal point : The first focal point of the lens is the focus of the first refracting surface . 
(This is the general form for understanding the real concept but you should learn the definition for each separately .  )
Hope it helps you 

Regards