New locomotive you create with menu Object/New... (or Ctrl+N), choose Locomotive. As name write identifier (case sensitive text, withou sepcial characters and withou spaces, should begin with railroad company letters (eg. CD for Czech Railways, or SNCF for French). This name will be also name of file, in which the model will be placed. Length, Height and Width are in meters, default values are for normal train. (Length must be mostly changed). If locomotive is different, if you look at it from begin and end (eg. steam locomotives), check the checkbox. Left and Right - the same.
If you click at locomotive, prview of it is displayed (new locomotive has empty preview), and you can fill technical data about train (Power,Speed...).
Title is text, which is displayed in VlakoSim.
Choose Object/Edit, and are in edit window.
First choose view from side (button 1). If you have allreadt painted picture from side, you can load it to internal POEdit clipboard (5), the press 6, move picture (with mouse) and then you must agree with placing of new picture with 7.
Shape is defined by clipping polygons from each side. The best is to try it, but simply teoretically : on the begin is big cube, an it is cut from each side with correct polygon, so that it can move throw the polygon.
Polygon is defined with its points (green circles). This points you can move (you must have turned of tool 4), insert new (2) or delete (3). With F5 you can see result of your work. Every side can have more clipping polygons, you can add them with Polygon/Add, sweitchin between them with Tab.
A few tips at the end: