Addition of “Leave A Comment” Button

I know my way around this script pretty well, but I’m no programmer, I’m wondering if anyone can help me out. I’d like to place a button (graphic) at the bottom of each post on the index page, there are simple links now, but if comments are open, I’d like for a button to be placed below the post to prompt people to comment. Can anyone show me how that code should go and where I should put it.

Thanks a MILLION!

blog url is https://slightlyunhinged.com