There are two different types of connection terminals – post and clamp.
Post

Fold the end of the twisted filaments of the flex back on themselves. Slacken the retaining screw in the top of the post and insert the conductor into the hole in the side.
Tighten the retaining screw and ensure that it is firmly fixed.
Clamp
Unscrew and remove the retaining screw top. Make a ‘U’ shape with the exposed end of the flex and wrap this clockwise around the threaded terminal.
Replace the screw clamp and tighten it down onto the wire. Ensure it is firmly fixed.

Both
The bare wire should be totally retained with no part sticking out. The insulated section should butt right up to the terminal.