To install the extension,

• Log in to the ftp, and then go to Magento root folder (generally present under the public_html folder).

• Overwrite the app, skin, js and var folders in the same sequence as illustrated in the following steps:
  a) Drag and Drop the app/code, app/design, js, skin and var directories.
  b) Finally, upload the app/etc directory.
  After the folders are loaded successfully, the extension is installed/upgraded.