Can you help with my blogger?

So I made a blogger. It's fine and all, but I want to add this gadget (Revolver Maps or something like that) and apparently I have to do it through a Javascript. Ok I have the script (?), but I know absolutely nothing about Javascripts and I don't know where to put it. Basically, where do I put the script so that the gadget will be added to the blog? Can someone please tell me a step by step process for adding it?