How to place the monitor and use the computer ergonomicly?

Hello there

ime using the computer to play games and lately ive stacked a pile of books below the monitor in a way that the middle screen of the monitor is pretty much at eye level so i dont need to look down and be hunched to see the info on the screen

the problem with this that im experiencing the whenever i move the mouse [i mostly use the mouse] all my upper body leans to the right , and it feels like my neck is also leaning to the right while doing it , and in fact i can feel it after using the computer that im walking balanced a bit to the right after this [sounds a bit funny but yes]

this problem doesnt happend when i put the top of the monitor at eye level but this isnt an ideal choice neither because lets say when im sitting naturally i see the top of the monitor and the screen pretty big so i do need to look down and bend the neck to see the middle of the screen.

and good advice for this?

and another question when im using the computer my desk is a little bit higher above my elbows and anyway my hand pretty much hurt after using the computer do you know how to stop this pain

and another question is it ok the use the mouse and keyboard while hand are leaning at the edge of the desk?