The best spice site I've seen is this one:http://www.uni-graz.at/~katzer/engl/index.html
However, there's no substitute for trying out the spices yourself, one by one. Buy a small amount of each, WHOLE, not ground, then use them to make simple dishes. That way you'll really learn what they taste like.
Start with the commonest ones ( pepper, allspice, cloves, cinnamon, cumin seed, caraway, mustard seed, poppy seed, etc) and then start surfing google for recipes with each. You'll learn lots, just like I did.