The release of Dwarf Fortress 2010 introduced many great changes to Dwarf Fortress, and this video will bring you up to speed on them. It also covers the beginning of a game, including preparing your dwarves, choosing a fortress site, and getting into caves.
Slaves of Arnok II: Dwarf Fortress, or Dwarf Fortress as it is more commonly known, is one of the most intimidating, challenging, and rewarding PC games in the world. It is totally free to download, available for Windows, Mac, or Linux, and would probably run on a 386. It's a text-based strategy RPG on an epic scale, where you create an empire starting with only seven dwarves and some paltry supplies.
If you're having trouble with it, you're not alone. It's really hard. Click here to watch other how-to videos covering many aspects of the game.