patchin: Yahoo's photo feature failed miserably, and instead they bought Flickr and is now using Flickr to serve photos.
Flickr does not use folders, instead they use a cool new technology called tagging. If you tag all your photos a certain name, and then search your photos by tag name, you'll get the photos only on that tag, and can send that link to your friends.
If you have a lot of photos, you can tag a bunch at once using the Organizr / batch tool they have. Read the help contents on Flickr, they're actually amazingly helpful.