1. Ok if you have set up a dedicated server you will need to open ports on your firewall look on
http://www.theavonlady.org/theofpfaq/index.htm under dedicated server ports and this will solve it
2. If your not running a dedicated server and would like just to host it from your ofp PC as in multiplayer/new then select your mission you will need to give all other players your IP this can be found by:
1. (XP) open MSDOS found under (start/all programs/Accessories/Command Prompt
2. (98)start/run
and then type IPCONFIG this will give you your IP (your address)
your friends will then have to open ofp and go to multi then click on the remote button and they have to enter your IP this should now let them see your game and connect i hope this helps
on the other hand if your are on a network you wont be able to host from your remote PC and you will have to set up a dedicated server on the main PC (the one tat connects directly to the Internet any way laters buddy good luck.