Well then I've just tried a bit. If that's the way to do it it is way less convenient than in the old Image Ready, that used to be sold together with but a seperate program from photoshop. It looks like one has to duplicate layers, to have one layer for each frame one wants, and then one has to put one picture on each layer, presumably using File>Place for each and every layer and pic. I can't see anyway to preview the result within photoshop itself (I've found a vid tutorial but not with pictures, and the person seemed not to have found any either...). The one has to file > save for web and click animate (and play around with the settings there if so desired). Still no way to preview it there!!! I had to stick my test in powerpoint to see what it looks like. So if really this is the way to do it...

what on earth were they thinking when they came up with that?!?!
BTW here's the
link to the youtube tutorial I watched (except he just draws shapes to illustrate; actually I can't even get the layers to appear at the bottom but that doesn't matter).