To edit an existing page, first you must locate it.
Here is how to do it:

1. Open the Dashboard

2. Click on [Pages] on the left hand menu, then click on [All Pages]

3. You will now see the All Pages list. You can find a page to edit by scrolling or searching. When you have found it, click on [edit]

4. Make sure you are in the Visual view. You will now see the page as you created it.

5. Edit your page content.

6. Save your work! WordPress will autosave your page from time to time, but you should also update your post as you go.

You can preview your changes by clicking on [Preview Changes]