hi barbra
thank you for the reply, I did what you suggest but when I hit save, and return to iphoto, there wont be any modified photo in the same folder there, only the original one.
except for No 2 suggestion, I was doing that already but its annoying. for instance Im student in molecular biology and we use images for gel electrophoresis, we need to edit them before puplishing,, in iphoto before using any external editor, I used to make correction (exposure/ croping/ filter etc in iphoto directly to the image) and it will be saved as it is. but with PSE11 this is pain, you have to do adjustment and save it on desktop, then in iphoto you have to import the image from desktop, I hope you get me now 
thanks again and any other suggestions if possible