A simple yet complicated question about Asian rail travel.?

O.K., so in a little less than a year, I'm planning on going by rail from New Delhi India to Beijing China. The problem is, for the life of me, I can't seem to plan the endeavor online. I can't figure out how much it will cost, (in U.S. dollars,) the best route to take, how long the journey will take, and several other fairly vital little tidbits of information. S.O.S.! I'm floundering!