I agree with Zeddie. Zbrush confused me at first too when I first jumped into it completely blind, but after watching a few tutorials I started to understand not only how it was different compared to other programs, but why these differences exit. And from that point on zbrush has become one of my favorite programs to use, a pure pelasure to work with.
This isn’t a program you can just jump into right away and press buttons with to figure out. If you want to teach yourself, then reading the documentation and the zclassroom videos are absolutely essential. Supplemental training from places like Digital Tutors, Lynda, Zbrushworkshops, or Eat3d will be a big help too. If a problem pops up and you don’t know what is going on, you’ll go a lot further by asking for an explanation and a solution than you will by letting it get to you. Don’t be shy or worry about annoying anyone by asking either. I’m sure the community would rather see a new user ask a hundred earnest questions than to have a single ‘omg zbrush sucks’ thread in their place.
When it comes to previous experience in other 3d programs, there’s only a few bits and pieces you can take from them. Mainly your understanding of points/vertices, edges and polygons will be useful, along with what happens when they subdivide, where and why you might want to add edgeloops, and how UVs work.
Otherwise, zbrush is actually closer to Photoshop at its heart. It is a painting program with additional orientation, material, and depth properties stored for each pixel along with its color values. Z + Brush. If you’ve ever used the newer 3d tools in photoshop then it might even look familiar to have a model floating above a 2d document. To this end, 3d models in zbrush are treated as tools. If I were painting a forest scene then I could load in or create several models of trees, and then stamp them all over my document at various depths to create the final image. Whether it was originally intended or just turned out by some coincidence over the course of its development, Zbrush became incredibly strong at creating and sculpting on its tools to the point where more people probably use that toolset more than any other feature.
After a few more hours it should start to be more clear that the document is not a standard 3d space and is independent of your 3d tool. You can clear the document at any time (such as it you accidentally enter quick sketch), and still have access to the tools that you were working on in the Tools palette. If you’re working on a 3d tool then you’ll likely want to save the tool and not the document.
There does not even seem to be somekind of select tool
You can select tools by clicking on them in the tools palette. When sculpting on a tool you can select any subtools that it consists of by opening up the subtool subpallete and clicking on them (or by alt+clicking on the subtool itself, or by hitting n), and when sculpting you can select individual polygons by using a selection rectangle or lasso.
the in-zbrush map/folder browsing is just plain hell on earth
I’m guessing you’re referring to Lightbox, which isn’t really meant to be a built in file browser for your entire computer (that is, I wouldn’t use it to load a file I have saved on my desktop or in my documents even though I could). Instead it’s more like having a Project Directory set up in other 3d applications like Softimage or Maya. It provides quick and organized access to files you have manually saved to your installation folder. If you ever start downloading custom brushes, models, alphas, materials… that you use on a frequent basis then it becomes very useful. For files that you’re not likely to use frequently enough to save them to your lightbox folder, then you might as well just stick with Windows Explorer.