rss feed widget -whats its URL

Hi I’m just trying to get RSS feeds to work. I’m no coder,and uncertain how this works technically but there is an rss feed widget to place in the side bar and its asking for the Rss feed URL. I also installed bloggroll widgets with rss feeds pluh in but thats asking the same. In setting up an account on technorati -its asking for an RSS URL – what is this and how can I get it working?

Hope you can help -Regards Martin