I'm trying to get the tags of a post on the single content page and displaying a list of other articles that share the tags with the post. For example, the user is reading an article with a tag like 'game'; I want to display the titles of other articles that share the tag 'game'. I'm basically trying to make my own "related pages" section.
How would I do this without using a plugin and which PHP file does the code go? I am using wordpress 3.2.1 and a child theme for the Twenty-Eleven theme.