. Trees and other scenic materials can be purchased commercially through hobby stores and on line. Some trees come ready made others as kits. There are quite a few people though that do scratch build trees especially. I am a mix. I like the commercial pine trees available through Woodland Scenics, but could find no good aspen trees, so I made them myself (and they looked good to if I do say so myself 
). A good place to start is by looking in a model railroad magazine, like Model Railroader, Model RailCraftsman etc., to get an idea of what is out there. Also find a good hobby shop and go in and talk to the folks about what you are most interested in in your scenery (desert?? Mountian?? Seaside??). Most hobby shop guys are the kind of people that will love to talk about scenics because everybody has their own ideas of what works best. While you are at the hobby shop, pick up a book by Kalmbach publishing called "Realistic Model Scenery." This book not only tells you HOW to scenic a railroad, it has great tips and pictures as well. Good luck, join us often and Happy Modeling!!------------------
The Santa Fe and Southwestern, Chief of the Southwest!