This is what you do.
Step One: Connect to your website using your favorite FTP access program. (example: Filezilla)(reason: the cpanel doesn't doesn't allow you to upload a whole directory, just individual files)
Step Two: Navigate to the directory where you installed wordpress. (example: www/mysite.com/wordpress/ or www/mysite.com/)
Step Three: Now look for the folder named "wp-content", and click on it.
Step Four: Click on the folder named "plugins".
Step Five: Now that you are in the plugins folder, drag and drop the plug in. ---Important--- If the plugin is more that one file, drag the folder where the plugin is located. (example: bling.php, bling_config.php are located in the "bling" folder, drag and drop the "bling" folder into the plugins directory, so the plugin will work.