Plugin development help

Hi

I need help. This is not about a problem is more like a push up start.

lets say I want to build a plug-in to add a button to the end of every post (eg. a retwitt button) what should i target to do it?

I’ve read a lot about it, but I really couldn’t figure out how to target the bottom of a post.

For now I’ve managed to do it by using a filter and hooking it to the “comments template”

add_filter('comments_template' , 'myFunction');

But since not all the themes have this “comments template” so my plug-in will never be “universal” .

What should be the correct way to do it? can someone give me a clue please?

Thanks!

MAC 🙂