Hi Ascension - we always end up on the same thread sooner or later but you know me, if Photoshop is mentioned, I have to comment. :)
I would normally agree with you on that - but in this case, with the difficulty of opening PNG files, I don't think looking through the different ways to open a file and the labelling of the interface sections are going to hurt too much.
But yes, from then on, you can go and raid the tutes here - after all, this is what you'll be using Photoshop for anyway! :)
Be warned though - if you ask a question that's covered in the first few sections of the manual, I shall not answer (even though it'll take every fibber of my being to do so); unless, of course, you're referencing a passage in the manual that you're confused about and then I'll try and swoop in before Ascension says 'I told you so!'
I've got to be quick as I imagine he's already loading it into his clipboard for easy pasting as we speak! :P
I know this thread is a few days old but in case someone had the same problem there is one solution that hasn't been covered. You can use File > Import instead of File > Open. This will immediately add your PNG as a new layer. It is imported as a smart vector object (I guess it's how it's called in english) so that it retains its original size informations and you can resize it multiple times without losing quality (with a normal object, once you scale it down you can't scale it up again without losing quality). If you want to apply filters to it, you'll have to right click the layer in the layer stack and choose rasterize layer, though.
I'll just throw in here that the help section of Photoshop is actually gotten pretty good. Also the classroom in a book series are good for beginners as they describe every step on the way :)