Is it possible to add a folder to my domain. I would like to add a weather program that is auto update and post it on my site but I need a folder in my domain called weather. Thanks

If you mean a first level folder called weather, no. If it can be nested inside another folder, yes. In your file vault under "file" you can create more folders. Just depends on how it's coded.

What site are you looking at? There are many ways to do weather stats if that one can't be adapted.

Many users embed weather widgets or you can link inside of a page using iframe (that's how I did our weather page).