Add "share buttons" in Footer post

Hi !

I want to add this code in the "footer" post on homepage

Please, Where should I add the code exactly (what .Php file, and at what line?)

Do you want it on the footer of each post?
teh easiest way would be to put some new widget area code at ago->Edit POST/PAGE INFO ITEMS-> FOOTER: xxxxxxxxxxx
depending on which footer area you want. Then use a plugin like 'exec php', add a text widget to the area and put your code there.