How to display a code of conduct/rules of use upon user login
Solution 1:
You want to set this in group policy. To set this you want to open up group policy management console (if you don't have it you can get it here) Your best bet is to set this on the default domain policy, right click then edit. in the policy go to:
Computer Configuration -> Windows Settings -> Security Settings -> Local Policies/Security Options -> Interactive Logon -> Interactive logon: Message Text for users attempting to log on
You can set your prompt there, also there will be an item "Interactive Logon: Message title for users attempting to logon" you can set an informative title for the message box there.