A png file is a graphics file. I suppose you could create a bunch of graphics files, of positions, puzzles, etc., and use these graphic files for training and analysis, yes. There are lots of programs that you could use to create them. My favorite is Paint Shop Pro.
However, if that's just a typo and you wish to save pgn files, then yes, of course that's also possible. Why wouldn't it be?
I think you should clarify your question.
Thanks for your answer. I want to save png. files here on chess.com
That would be a nice feature. Without detours such as blog entries.
Something like this? I don't think you can download these, but you could take a screenshot.
Sorry, I always write PNG not PGN 
I use now this for Mac.
Hi,
I like to save .png files for training and analysis … is this possible?
Thx