Create your poster using a word processing application. Make the page size at least 11x17 inches, since a large poster is needed that's easy for patrons to notice.
Write your poster with a beginning statement regarding the closing and opening hours of the computer lab or room. If the computers have a sign-in sheet and time limit, mention this as well.
List personnel who are authorized to turn computers on and off. This might include yourself, a teacher or a member of the IT staff.
List any other actions that users are not allowed to carry out with the computer, such as downloading illegal torrents, pornography or installing software. Make it clear that the lab will hold patrons responsible for any damages that result from violations of these policies.
Mention the limit (if any) for printing documents. If your lab charges for prints, list the fees for both black and white and color prints.
List the penalties that users face for violating these rules. This could include the cancellation of lab privileges for minor infractions. But make it clear that if damages result, the patron can be held financially responsible for damaged equipment, network down time and IT labor. Include a number at the bottom that users can call for further information, questions or to file complaints.
Print the computer rules poster on heavy stock card paper so that it will last. Hang it in a prominent place, such as over the printers.