very unpolished page
so basically how you make glitch art is you get a file and then make it go wrong (intentionally)
this is all for mac so it might not work for windows.
my general tips are to not mess with very start of any file, because that usually breaks the entire thing. and always save the original copy unless you want to lose it, and probably save WIPs too.
With TextEdit
download an image file. i know JPG works and i think PNG works too?
open the image file in TextEdit. start changing small bits of the gibberish while looking at the image to make sure that you aren't breaking it in any way that doesn't look cool or fully breaks it.
With Audacity (i learned this from here)
get an image (i think you need to convert to bitmap .bmp or .tiff) and turn it into a .RAW file. i think you can do this on photopea (open the file and save as .RAW). if your image has weird dimensions, you need to record those or else it'll be hard to get it back. import the .RAW file into audacity (File>Import>Raw Data...). make sure to set it to "U-Law" in "Encoding:" when you import and export. select parts of the gibberish audio and apply some random effects to it. but, don't do anything to the very first part (like the first 1%) of the file as this will basically always break it unrecoverably (in a visually uninteresting way). also, making the file longer will probably break it.
here are some effects that i remember looking cool: everything in Distortion and Modulation, Delay and Reverb effects, invert, compression settings change it a little
then you export it from audacity as a .RAW file. make sure you set the pixels and channels right or else it'll glitch too much (if you want this effect, see below). then you put that .RAW file back into photopea and export as PNG/JPG/etc.
RAW Stuff with Photopea
get an image. export it as a .RAW file. then, import the same file but mess with the settings when you import it. changing the dimensions, bit depth, channels, etc.
there's also datamoshing which i haven't researched yet