File manager allows you to manage and edit the files right inside the cPanel interface. You do not need to download/upload the files or require any special software on your computer to edit them. Although this method can be used to create entire website however it is meant for quick fixes or edits on the fly. Normally you would want to keep a local copy of files that you maintain and edit in a developer environment such as Adobe Dreamweaver.
You can access the File Manager under Files section as shown in the screen shot below:
Once you are inside File Manager, you can see your main folders on the left side, and the files and folders in it in the right pane. Double click to go inside a folder to see the files. Click once to select a folder/file, and then you can take several actions from the toolbar:
You can also learn some of the features of File Manager in cPanel documentation.
We hope the File Manager can be a handy tool. If you need any assistance, please contact support.