Unable to change theme colour in Magento

"What you can do is check that settings is not overrided on different scope level like website or store view
Scope switch is located in top left corner of Configuration page
More info about scopes - http://queldorei.com/faq.html#basic_6"

Command to login ssh

You may not be able to unzip a file via ftp.

Log into ssh using
ssh username@serverName.com
then unzip

Where do I add a Meta tag for Magento?

Just edit app\design\frontend\default\default\template\page\html\head.phtml and add the custom meta tags in there. Or maybe the path is different if you set up a new template for your website (maybe app\design\frontend\yourtemplate\default\template\page\html\head.phtml)
or
Please go to System > Configuration > Design > Html Head and edit “Miscellaneous scripts” field. Unfortunately this works only for static information / meta-tags.


See more about SEO on Magento:
http://www.screenpages.com/about/articles/seo-in-magento