Now someone else may help out more with the items, but about the images: Can you describe exactly what you're doing to "change it"? Like, step by step? Cause it should be pretty simple to input the URL. And yes, this site mostly doesn't let you "upload" pictures (500x500 max, and there's a 100kb file size max I believe), you need to upload them somewhere else and then link to them.
Or do like I do and have shitty small images, which you upload by going to "My stuff -> Pictures" and then uploading there.