@Iovimare (trying to explain the process) (on photopea) if you have a gif and a psd colouring (which you can find on tumblr and deviantart) downloaded you should open them separately (file>open, not file>open & place) and then move the folder with the filter(psd colouring) over from its tab to the gif one. and if you want to move the gif you have to go select all the layers of the gif! and if you want to make your own filter you go layer>new adjustment layer and whatever thing you want to change with the colours/brightness/contrast/etc etc