There are so many errors, ommisions and inconsistencies in the Sharepoint documentation that you have to resort to direct experimentation to get even the simplest task to work.
Currently I am trying to add a simple web part to a Sharepoint site. This should be easy.
The documentation claims that you can freely choose to use either ASP.NET web parts or Sharepoint web parts (both randomly abbreviated to web parts). Once you get through all of the wierd hurdles required to get a web part to install into sharepoint (Add the manifest file with the correct syntax noting that there are several flavours of manifest files).
There is a lot of cargo cult programming going on with this product (such as rename cab files to dwp before installing them – which is not required).
Once I got a classic asp.net web part installed I was kindly informed by the web page editor that my web part may not be put into a web part zone.