While I don't completely understand your problems and it would be helpful if you could post what you've done, here are some thoughts that might help. You can set the window in Poser to a particular size. Render to that size. If you want to render to another size and shrink in a paint program then remember when you resize to maintain the original aspect ratio (How you do this is a function of the paint program you are using). A good size depends on what resolution you design for. I have chosen to design in 800x600 resolution with no more than 350 pixels wide by 500 pixels high at 72 dpi for my particular applications. When you place the picture on the web use either jpg or png. Depending on the quality in jpg your picture can be made to load quickly but not look as good, or load slowly and look better. I had terrible luck trying to use a alpha type channel in web design and just made my background in Poser the same as what I designed for the web page.