1) Open Steam Website In Browser (Google Chrome)
2) Click On Your Profile And Find "Images"
3) Choose Your File You Want To Upload
4) Press F12
5) Type Which Command You Want To Use

- Long Artworks:
document.getElementsByName("image_width")[0].value = 1000;document.getElementsByName("image_height")[0].value = 1;

- Screenshot Artworks
document.getElementsByName("file_type")[0].value = 5;

HOPE THAT HELPED!