I didn't see any guide on how to join a server, so i'll explain it myself
Installing FreeSO(Skip these steps if you already have it installed and working):
1.Download The Sims Online from Here:
http://largedownloads.ea.com/pub/misc/tso/Setup The Sims Online.exe
2.Install it on Drive C(May cause problems on other hard drives)
3.Follow the installation steps, when it asks you for a CD Key cancel the installation
4.Download the latest FreeSO Dist here:
http://servo.freeso.org/viewLog.html?buildTypeId=ProjectDollhouse_TsoClient&buildId=lastSuccessful&buildBranch=<default>&guest=1
5.Extract the Dist ZIP file with WinRAR, WinZIP or any other compression/decompression program on The Sims Online installation directory(Usually C:/Program Files/The Sims Online/TSOClient)
6.Extract the extra packing slips from here:
https://dl.dropboxusercontent.com/u/12239448/packingslips.rar to The Sims Online installation directory, into the existing packingslips directory.
7.If the game doesn't work, try downloading updated Graphics Drivers and OpenAL or connecting a sound device (speakers, headphones, etc.)
Joining a server:
1.Look for servers on one of these pages(Or get the server IP/Address from the server owner):
1.Once you have the IP/Server address copied or written, open FreeSO.exe in your TSOClient folder in your TSO installation directory(Make sure the server uses the same dist/version as you)
2.Open FreeSO.exe
3.Create your Sim/Avatar(No need to create it every time you launch the game, it will get saved)
4.Click the "Search Icon"
5.Type the server IP/Address here:
6.Now click on exact match and wait!
Tips/Troubleshooting:
1. If while connecting to the server the bar gets stuck at 0%, maybe the server is closed or using a different version, also check if you wrote the address correctly
2. If it gets stuck at 25%, wait longer, try updating the version or restart the game
3. Not working? Try downloading updated Graphics Drivers and OpenAL or connecting a sound device (speakers, headphones, etc.)
4. Want to create a server?(Thanks to LetsRaceBwoi):
http://forum.afr0games.com/index.php?threads/how-create-your-own-server.649/
Hope this guide helped!