I am looking to make my sites banner appear the same for all screen resolutions, but it seems when I make it large, it doesn't appear for anyone below 1440x900, and when I make it small, it appears tiny and in the left hand corner for anyone with a resolution above 1080x720. How exactly can I make it appear the same for everyone? Note: This is for an IPB forum.
People have may different settings so you probably have to detect the screen resolution and serve a different advert?
When it comes to ad banners, you should stick with the standard banner sizes like 468 x 60, 160 x 600, 125 x 125, etc. But I think you are referring to your website header image size? If you make it a fluid width (100%) then it should stretch across the screen but probably won't look too good. Your best bet is to design it for the most popular screen resolution which is currently 1024x768.