How would you make a telekinesis script using raycast?

I been studying "Telekinesis scripts" and I'm not sure how to make one myself. In all honestly, the only part I "Know" is raycasting, But even then I dont understand it.

How do you make a script when a player joins a server, they have a script where whenever they click and hold something while the crosshairs are pointing at it, it picks up a unanchored block and floats right in front of their camera, and stays in front of the camera, even when they turn, But if the block is anchored it doesn't pick up?

If someone could explain this with detail, I'd be sincerely grateful.

I'm sorry I didn't put a script here, but I was only studying scripts, and I didn't see anything on the wiki.