To run Server Messages you need to add a few lines to your pbsvuser.cfg file, you can find this file within clanforge > profiles > configs(tab at top) assuming you have the punkbuster addon enabled.
Simply add the following under the Punkbuster tasks part of the file and replace the server messages with your own:
;pb_sv_task X Y "MESSAGE HERE"
;X= Number of seconds after server start to say message
;Y= Number of seconds before repeating this message
pb_sv_task 60 600 say "Welcome to the ^5Multiplay ^2clan name ^7Server."
pb_sv_task 120 600 say "^1message 2 here."
pb_sv_task 180 600 say "^2message 3 here"
pb_sv_task 240 600 say "^2message 4 here etc"