1. Download the package 
  2. Unzip and upload the files to your server
  3. Navigate to http://www.your-domain.com/install.php
  4. Fill out the required information and save
  5. If you installed Cosmo in a sub-folder, you'll need to manually update the .htaccess file. Change the line:

    RewriteCond %{REQUEST_URI} !^/uploads/
    AND
    RewriteCond %{REQUEST_URI} ^/api/

    to 

    RewriteCond %{REQUEST_URI} !^/YOUR-FOLDER/uploads/
    AND
    RewriteCond %{REQUEST_URI} ^/YOUR-FOLDER/api/