If you see a warning that the page already exists, you've chosen a name for your file that exactly matches another file already located in your File Manager.
If you wish to keep both files, save the new file under a different name by changing the name of the file you're trying to save in the field provided, then click "Save." You should no longer see the warning. If you want to replace the file that already exists in your File Manager, go ahead and save the new file with the same name.
Note: When Yahoo! sets up your account, we add a default "index.html" file to your directory automatically. If you're trying to save a file called "index.html" file, you will need to replace the default page.
Also, please be aware that if you FTP a file with the same name as one already in your File Manager, the original file will be replaced without warning you first.