How do i make main player's weapon shoot at the direction of the click? (mobile)

Hi!
So,i'm making a 2D shooting game and i want the player to shoot by clicking somewhere on the screen,and the weapon will rotate to that direction and shoot.
And i have very little idea on how to do that.
Simple as that; The player click anywhere on the screen,the weapon rotate to that position and shoot.
Can someone help?
Also,sorry for my english!

 

this is a bit old, but I think it should still work today