http://www.diabloii.net/

This is a pretty good reference for D2Lod gameplay, the way I learned how to play was simply playing it, I cleared everything and experimented with the stats and skills.

But you'll learn fast to have a well balanced character in order to defeat the higher difficulties, as in Atleast one skill with significant damage from each of your skill trees.

But I'm sure someone else can give more advice.

"When the people find that they can vote themselves money, that will herald the end of the republic."- Benjamin Franklin