we call customized view the analysis that the user save after a navigation or elaboration of data. For this motive you can create by the Olap Engine, Geo Engine or Qbe Engine.
To create them you should execute the document, use it with a navigation (ie. with the olap you can drill down some dimensions) and at last click on the disk icon (Save option). With this last operation you can set some usefull informations to recognize it and so you have created a new customized view. To launch it you should launch the same document and select it in Customize View section that you found in the execution page.