If you're new to SketchUp, start
here. Those training videos will help you with the basics (often all you need to know.) SketchUp is very intuitive so learning it is easy, but takes a little time. Also, keep in mind that there is a
3D warehouse that contains 1000s of pre-made SketchUp models ready for download.
If you looking for more advance instructions, search YouTube and Google, as well as other places for tutorials, there are 1000s of them on the web.
Here is a SketchUp user manual pdf file that you can use as well.
Remember, there are already 1000s of models available for you to use for FREE, so search there before trying to make complex models that have already been made.
Go
here for more information.
-Hope this helped.