When clicking on the attachment symbol, it brings up both a browse search bar, and a URL address bar. The browse is directly above the URL when I open mine.
There are two different ways to upload images into a post. One is the attachment symbol (the teeny paperclip), and the other is the image symbol, the one Kreskin was talking about. The attachment option lets you attach a photo from either your computer or a URL source (such as photobucket). The image icon allows you to imbed a photo from a URL source, such as photo bucket. Simply copy the link location of the pic you have in photobucket, and paste it into the URL bar that pops up when you click image.