Most of the time there's a server with people on it, but it gets very popular late-ish afternoon US time throughout the night daily, or for me, being a Euro, very late night/early morning daily :P, especially so on weekends. And the game is becoming more popular. The pickup community play several times throughout each day usually.
As well as the excellent interactive Training Fortress Forever offers through the main menu, if you need any extra help, I and others will happily join you in game and teach you all of the basics, advanced techniques, and explain the game in detail to you.
Just ask
, and I'll add you on steam and walk you through anything you want to know or learn.
- FreaK