Learning MFC

Im trying to learn MFC by taking on a small project of making a sort of 2D modelling tool, which just really lets you draw dots and connect lines to them in a heirarchy format, sort of like bones in traditional 3d modelling tools. You could then just move them around. But I''m having some trouble, and here are my questions: 1) What part of doc/view architechture in MFC is responsible for creating multiple frame windows? Do I have to derive from the default class they supply when you create it or just add it in? Or something else? 2) If I have a class which had representations of bones/lines which was made before I tried to put it into MFC, where should I put this code? Should it be moved into a class derived from CMyAppDocument? Or into that class itself? Sorry If im asking some questions which have been asked before, but I havent found them in any threads before. Any help is appreciated!