The No Entry 8001 sign will have the picture of a hand preventing somebody from going any further on top and the written words below. To keep people out of a certain area, this sign can be very beneficial and it should not be disobeyed.
If an area is restricted or prohibited, people will need to be informed. You should ensure that this sign is displayed very prominently so that your wishes are carried out at all times.
Fixing requires anything as simple as sticky pads, 'No-nails' type adhesive or double-sided tape.