So it all depends on what you are trying to do. I learned how to use the deep material editor by playing around. Susan Kitchen's book on Bryce is an awesome encyclopedia for the deep texture editor (and everything else about Bryce ;-) and will take you beyond what you can learn by just experimentation. If you are trying to make a picture texture, very simply, whites are high and blacks are low and there's 256 layers or so. One could use a picture editor like photoshop, or paint shop pro, or my favorite, Corel Photopaint, and turn a color picture to a grayscale image. Then use that as a template to create highs or lows. In a picture material, one can only have one alpha channel, so if you want a transparency effect with different locations of emphasis, one would make a separate material for the transparency channel. I know I've generalized this, I hope its enough to get you started!!