I'm looking at adding a new post button, a happiness button, as it were, that will track how "happy" a post is. 

But I'm at a complete loss on how to get this done. I know I need to:

Add the button

Modify the Database

and set the button to increment the field in the database entry for the post, 

but where on earth is the file I should modify to add the freaking button? and how would I go about modifying the database?