Why the force is going downwards according to right-hand rule while the magnetic field is going inside the screen? I was reading magnetism concept from Giancoli physics 7th edition and I came across this statement.

Image of an electron flow in the magnetic field is as follows:

My argument is if we apply right-hand rule here than the resulting force should be outside (or upward to the top) the circle that is depicted in the second picture. 
Now I am confused by the force direction in the second picture and the highlighted statement in the first image. What does he mean by "reverse the direction for negative charge"?
 A: It means just what it says: the direction of the force on a positive charge moving through a magnetic field is indicated by the right hand rule.  The force on a negative charge moving through the same field is in the opposite direction.
One way to apply the right hand rule for determining the direction of the cross product of two vectors is to point the fingers of your right hand in the direction of the first vector, and then curl them in the direction of the second vector (this forces you to point your palm in the direction of the second vector). If you extend your thumb while you do this, it points in the direction of the result of the cross product.  
So, for magnetic force on a moving charge, given the equation $\vec{F}=q\vec{v}\times\vec{B}$, you point your right fingers in the direction of motion of the charge (to the right at point P in your figure) and then curl them to point in the direction of the magnetic field (into the page). Your thumb now should be pointing up toward the top of the page, so this is the direction a positive charge would be pushed.  The electron, having a negative charge, feels a force toward the bottom of the page.
