i m doing content management system for my company website.i have a problem.how to edit files.if anybody knows idea about this then plz help me

What are you talking about? Without a few details, it's not possible to imagine an answer.
What kind of files?
What do you want to do to them—exactly?
Try to put the idea that is in your head into your question so that your need winds up in the head of the person reading your question.

helo brain
i want to edit files and allows to user change in them.i.e. contents,images etc. if u have any idea then plz help

i think if you want to change the text content you have to select each one then open it with IO stream classes, and about the images .. i think it's difficult to user image processor classes at the run time code, i preffer to make ability to download/upload text & image files and change them as you want.