First of all, you need to be aware that editing using the inspector in a browser only changes things in that view of the page in your browser - as soon as you refresh the page you lose the edit. Any edits you make this way will not be permanent. You need to find the file on your server. It will (probably) be in app/design/frontend/your_theme/template/page/html. You are (probably) looking for a file called head.phtml.
You can find the path to teh correct file by turning on template hints in Magento system>configuration>developer>debug . Make sure the current scope is set to default store view. Warning - this will put big red ugly things all over the frontend of your website so best do it on a development site if you can.
This should be enough to get you started.