1. Extract the .zip file you downloaded from CodeCanyon.
  2. Upload only contents of "website" folder to your server (same place where files were uploaded during installation) and overwrite old files.
  3. Visit http://yoursite.com/update url and click Update Now button (Make sure you are logged in as admin).
  4. Once update is completed you will be redirected back to homepage.
Note:
No users, data, uploads or settings will be lost on your site when applying updates.
Important:
Always use a desktop application like FileZilla to upload files to FTP as opposed to web based file managers to avoid issues with corrupted or not properly uploaded files.