You can do as they said, but then that would require that you pay for each additional photo(the first one is free.
What I do is, I edit the photos so that they are 800xXXX resolution, then upload them to photobucket. Then, while editing your listing on ebay, you will notice a button that says HTML, clicking on that will let you edit your listing description in html format, which will also let you put photos in html, which you can get from photobucket because they have an html link for all photos. This lets you put as many photos as you want without paying any extra pretty pennies, and also looks better than just putting links on it, which technically can get your listing removed because links to outside sites are against ebay policy…even for pictures.
Oh yeah, if you do it my way, there are NO restrictions on photo size, I just think that 800x600 is about the best size for it…i have over 220+ positive feedback there, so I kinda got used to everything