See the read me file tha is on the computer in the freelancer Data file or see below -

IV. Multiplayer Guide
When you run Freelancer for the first time it generates a unique ID for your system. When you connect to a server, the server program takes the ID from its computer, combines that with your ID and creates a new ID which will then be associated with your characters on that server. What does this mean for you? No Usernames or Passwords to remember. It is important, however, that you write down or print your identifier, as losing it may result in the inability to retrieve your multiplayer characters from the servers on which you play. Freelancer includes a utility for retrieving your ID. The utility is myflaccountid.hta and it can be found in the Freelancer\exe directory within your install folder or you can run this file from the Start\Programs\Microsoft Games\Freelancer\Examine My Account ID shortcut.

Connecting to a Multiplayer Game
Launch Freelancer, click Multiplayer, select a server with an open player slot, click on Connect and you’ll be taken to your Character Selection Screen for that server.

The Character Selection Screen will list any characters that you have on this particular server. (All multiplayer characters are saved on the server, so you cannot take characters from one server to another.) Select the character you wish to use, or create a new character, and click on the Load Character button to launch your multiplayer game.
Server Setup
In order to run a Freelancer server, you will need to launch FLServer from the Windows Start Menu. The computer running the server may also run the client at the same time and play on that server, but keep in mind that Freelancer will run slower on a system running a server in the background. For the best multiplayer performance, try to run the server on a dedicated computer (one which is running just FLServer and nothing else).

In order for Internet players to use your Freelancer server, that server must be made accessible to them. If you are not using a firewall, router, or Internet connection sharing to access the Internet, then your server should have no problems allowing people to connect to it. However, if you are using a firewall, router, or Internet Connection Sharing, then you may have to do some additional work to make your server accessible. See below for more information, or look at the ReadmeServer.htm file in the Extras directory on the Freelancer CD.
Firewalls
Freelancer uses the standard DirectPlay ports, so your firewall needs to pass UDP ports 2302-2304 to the server machine.

Freelancer clients do not require any firewall configuration.
Network Address Translators (NATs) & Internet Connection Sharing (ICS)
These technologies allow more than one machine to use a single network address for connecting to the Internet. Microsoft’s Internet Connection Sharing is one example of this kind of technology. (Windows 98® ICS users will need to configure and install the win98ics.inf file found in the Extras directory of the Freelancer CD; see also ReadmeServer.htm in that same directory.)

Only one Freelancer server can be run on the LAN side of a NAT or ICS setup. For NATs that require manual configuration, UDP ports 2302-2304 should be forwarded to the computer that will be running the server.

Freelancer clients do not require any NAT/ICS configuration.

Manually Connecting to Freelancer Servers
Freelancer.exe supports a command line parameter for manually adding servers to the list of potential servers. This advanced feature requires that you know the hostname or IP address of the server computer as well as the network port on which FLServer is running. It is useful for playing on servers that are not on your LAN and are not advertised on the global server.

To add a server to the server list, use the following syntax:
FREELANCER.EXE -s<hostname>:<port>
where hostname is the name or IP address of the server computer and port is the network port number on which the server is running. You may add multiple servers by repeating the same syntax. See the ReadmeServer.htm file in the Extras directory on the Freelancer CD for information on manually setting the network port on the server.

Servers added in this way will not appear in the list of available servers until the respond to a ping request from your computer.

Examples:
FREELANCER.EXE -sCoolServer.myisp.com:2302

This will add the computer CoolServer.myisp.com to the list of potential servers; it will be pinged on port 2302.

FREELANCER.EXE -sA_Sever.myisp.com:2302 -sAnother_Server.yourisp.com:2304

This will add the computers A_Server.myisp.com and Another_Server.yourisp.com to the list of potential servers. A_Server.myisp.com will be pinged on port 2302 and Another_Server.yourisp.com will be pinged on port 2304.