Edit Meta-Tag for Affiliate-Program

Hi, to promote products of an affiliate programm I have to validate my blog 1.either by entering the following code in the HTML-Meta-Tag. <meta name="verification" content="a496ea736668708e33f8f4ebf0bfbc76"/> 2. or by uploading an .xml-file. I tried to do this step by creating a new page, which is displayed at the home page. But it didn't work. I also need to edit the meta-tag for Google and Bing. Could you please help me with my issue? I am a newbie and couldn't find this meta-tag in the css code. Thanks a lot, Jonas