I try to design some icons for gnome (symbolic icons) but the problem is that gnome files make them completely black(it fills the transparent areas in the icons) how i can solve this problem
Use SVG or PNG for the image file of the icon.
https://specifications.freedesktop.org/icon-theme-spec/icon-theme-spec-latest.html
Some other image formats don't support transparent white space. I recommend testing your icons in an image viewer that supports white space. If you get a similar effect, mind this is not in the editing program so what your seeing in the image decoding library making sense of the image, then you should try to change image format to a different format that supports transparent white space. If you are using Gnome, Eye of Gnome, the default image viewer, should show a gray checkered pattern where there is white space.