Choosing your server software
The Software tab for TF2 has a single option: the Public branch, with no alternates to choose from. Any change here requires a server restart before it applies, and the panel confirms this before saving — restart when the server is empty to avoid disconnecting players.
Default server configuration
Your server ships with a default server.cfg that includes an auto-generated RCON password, which authenticates remote console commands sent to your server. You can review or change it, along with any other settings in server.cfg, through the File Manager.
Next steps
Once your server.cfg is set, check the Console tab for a clean startup. There's no automated mod manager for TF2, but SourceMod and Metamod:Source are the standard way to add plugins — see Installing Mods on Team Fortress 2 for the full install steps. Back up your configuration before making changes — see Managing Backups & Restoring Your Server — and use Scheduling Automatic Server Tasks to automate restarts.