go to CONTROLS (last button on EDIT NAVBAR)

click on link: MULTIPLE IMAGE UPLOAD

upload the ZIP file just like you upload an IMAGE

STUFF YOU PROBABLY DON'T NEED TO KNOW
• all files must be named same as orderable items 1234.jpg should match 1234 ID
• the zip file shouldn't contain an IMAGE without a matching file. If it does, Yahoo Store just stalls and all the files after that do NOT get uploaded
• the ZIP file should be a Y!Store friendly 5 megabytes or smaller IMHO
• the JPEGS / GIFS inside should be no more than 80-90K each for load speed / Yahoo filter reasons
• if you get the RED SQUARE where the image should be, either the IMAGE was too big (file size wise) or not a JPEG or GIF format.