usuing a custom page template: looking for php code to show all posts by tag

i’m using my own page template so i can have static content, then all the posts of a certain tag below it.

simply put, i’m looking for a few lines of php that will show all my posts that are tagged under category ‘x’. if that makes sense. i know this code it all oer the place in main index template but i’m not sure what it is.

thanks.