Inserting Advertisement Unit Twenty Twelve

Hi
I am using Twenty Twelve child theme. I was approved by Yahoo and Bing Media.net Advertisement and was unsuccessfully trying to add ad units to my blog http://www.the-gorod.com
I want it to show in a middle of posts and one on a right side bar. I tried to modify my child function.php and as for sidebar i used text widget and inserted code there, different unit sizes, different location, but each time add units just shift all the way down the page, under footer. I prefer not to use plugins. Anyone who experienced same problems please help me. Thank you for your time guys