If you go to the fps creator homepage and click on the download link at the top of the page . on that page there is a link to download an entity creator. when you download that watch the tutorial video that will teach you how to use it. It will convert any .x files into .fpe.
If you want to make .x models go to http://www.thegamecreators.com and in the 3d models category at the top click on 3d canvas pro. You might find it useful. I am pretty sure that is shareware but it is a useful trial version and you will be able to find a purchase link on the game creators website.
I hope you found this useful...
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