hi where can i find the posts_by_tag() function

hi thank you for the this plugin and a question ;
i need to turn this plugin right to left so i need to change not only the css but also the layout (the php).for example i want to put the title before the image .
whice lines i need to change in post-by-tag.php file to change the layout?
thank you

https://www.ads-software.com/plugins/posts-by-tag/