We include TF2 with all dedicated servers, so it should actually already be on your server. It would be in "c:\game installs\sourcebase\orangebox", since it's based off Source.
But, you'd still have to update it to the latest version. You can do that by opening up a command prompt and entering these commands:
hldsupdatetool.exe -dir sourcebase -game tf -command update -verify_all
After running the update, you'll be able to run the game server by executing srcds.exe in the "c:\game installs\sourcebase\orangebox" folder.