Battle for Moscow does an excellent job of translating Chadwick's newbie-friendly rules to the PC. In the course of playing the game, you will learn numerous tabletop wargame basics including hex movements, zone of controls (ZOC's), how combat odds work, the importance and mechanics of supply and reinforcements, calculations of rail movement, the effects of weather on combat, and more. The game is played in traditional turn-based format, on a 16x10 map with an average of 50 units. There are 2 scenarios and a full campaign that lasts for up to 14 turns.
Unfortunately, Battle for Moscow has no computer opponent, so you will have to either play against a friend on the same computer, or use the Play-By-E-mail (PBEM) feature. But as a computer aide that introduces you to the genre, this freeware title offers excellent value. Recommended - but only if you can find a vic... err, a friend to play with :)