You can do so much with DNN that I think even an expert .NET web developer needs a good deal of time and experience to become thoroughly familiar with its many possibilities. However, a "plain vanilla" installation is a much simpler matter. To get up and running quickly with it you can spend a few dollars for a host with a one-button installation and then you're able to focus immediately on questions like what you describe...skinning, etc.
You'll need to stick with it for a bit. Don't underestimate the value of these forums, whenever you run into a specific challenge you can search these forums, or the older archives at forums.asp.net, and quite likely find an answer. Otherwise post the specific question and it can often save you hours of time.
In addition, besides the documentation available on the downloads page, have you looked at the other resources on the dotnetnuke.com site? There are videos here:
http://www.dotnetnuke.com/tabid/810/Default.aspx
There is a good, but by no means comprehensive list here:
http://www.dotnetnuke.com/tabid/468/Default.aspx
There are also some training videos available for purchase here: http://www.snowcovered.com
If DNN were so simple that anybody could "get it" in minutes, it would not be a professional-grade framework. However I don't know of any other CMS which does as good a job as DNN of providing help and resources to make it as easy as possible for the uninitiated, while also providing the flexibility and power to sustain an ever-growing community of professional developers. I know it takes time, but I encourage you to stick with it, the benefits are unparalleled!