There should have been some kind of connection between the center wire and the frame of the dryer. A jumper wire or a metal strap that was connected to the center terminal.
That jumper connection needs removed and the new green wire goes where it was attached to the frame, or sheet metal, of the dryer. Not the terminal with the white wire - the other end of the jumper.
If your dryer had no jumper the you will need to find a screw somewhere on the frame to attach to. It won't matter much where, as long as it is not one of the red, black or white termination points.