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I'm sorry, Macbook 2,1 is a 2006-2007 model and that model not compatible with the latest Mac OS X 10.11 El Capitan. So you will not be able to update the Safari to latest version. You are probably already on latest Safari that your Mac can handle. Do all software updates from Apple > Software Updates.
However your Mac is compatible with the another browsers like Firefox and Chrome. So install latest Firefox or Chrome and you will be able to use or browse all websites.
Download Chrome from here --> https://www.google.com/chrome/browser/desktop/
or download Firefox from here --> https://www.mozilla.org/en-US/firefox/new/
If you have any questions or would like any additional information, please don't hesitate to ask.