You can insert legal warnings or any interesting messages for others
just before logon to windows based computer. This is very useful if you
want to give a message to new users about the uses of computer. You can
create this banner message
using the windows registry editor but make sure before modifying your
system Registry about its backup because Registry contains all
information how your system runs. This backup will help you to restore
Registry in case any problem occurs after modifying.
To edit the computer registry, first you should log onto your computer
with administrative rights.
Click Start button then type regedit in Run option
then press Enter for next.

Here locate the location to:
HKeyLocalMachine\SOFTWARE\Microsoft\WindowsNT\CurrentVersion\WinLogon
Here in right side panel,
double click on the key
LegalNoticeCaption
and give it a value you want to see in the menu bar. For example “Welcome
Screen for
All Users”.

Now again in right side panel,
double click on the key
called
LegalNoticeText
and change the value you want to see in the dialog box. For example “You
may not succeed later when trying to logon without a password.”

Now close the registry editor and restart your computer after any
changes to go into effect.