I'm using magento 1.4.0 and when I try to get to magento connect and download a plugin the page will say

Error: Please check for sufficient write file permissions

Your Magento folder does not have sufficient write permissions, which this web based downloader requires.

If you wish to proceed downloading Magento packages online, please set all Magento folders to have writable permission for the web server user (example: apache) and press the "Refresh" button to try again.

does anyone know how I can fix this problem,

thanks

Update: the plugin I'm trying to use is MagentoPycho light box so I unpacked the folder into the app/code/local but it still doesn't show in the admin area