widgets–totally lost

I had google ads appear in my new URL…I found a location with the HTML code for widgets in my dashboard…I replaced the pub number with my correct pub number…I went to a page that said to move the widget to a sidebar to activate it….I moved the widgets and saved. now all the google ads have disappeared and are replaced by blank space. A statement below the box of wedgit html code state copy the code in the box provided, I can find no other box other than the box of code in which I corrected my pub number. I am completely lost, help please