Third Person Camera Challenge (C#)

Hello all! I am pretty new to scripting in C# and I am kind of stuck here I am making an adventure game, kind of a tell tale game, but the camera seems more like resident evil 5 and 6, where you have a cursor. So...I'll try to explain everything. The player have a cursor to interact with the world. The cursor will be in ScreenPosition, and the head of the character must follow the WorldPosition of the cursor. (the cursor will move on the XY axis, and won't rotate the camera, the rotation is another matter)

I guess that the ray from the camera (I forgot the name of the funcion) can give a collider back, making the position of the rayHit backk as the new LookAt. And if the ray didn't collide with anything, make a float range set as the ray,getpoint (range) as the new lookat.

My problem is how to exactly put it all together. I know all the logical steps and then proper functions, but I can't seem to make the script on my own! So basically, I want to make a cursor that will move on screenposition, with the mouseInput. and then make a object that looks at the worldposition of the camera ray.

Any help given is deeply appreciated! Thanks!