If you mean that you want to rotate an image taken in portrait mode, i.e. with the camera turned 90deg from it normal orientation, P182 of the manual.
Normally, when you take an image it should auto-rotate, but if you look on P183 you can see how to turn that feature on and off.
If you don't have a copy of the manual (you should!), go here to download a PDF copy. pssx50hs-cug-en.pdf (c-wss.com)