Good evening Kayhan and welcome back!
Thank you for reaching out to us.
I would love to help you with this topic.
What is going on is that your site is already using some form of calendar template customization.
You can usually see those in the /tribe-events/ folder of your theme.
The good news is that you can easily tweak those templates.
You might want to read our Themer’s guide to get a sense of how that works.
If you are still unclear on how that works,
Could you please send me a copy of your WordPress theme / child theme in a .zip file link, in a private reply (via Dropbox or Google Drive) so that I can run some tests on my end ?
Please ensure you are using the latest files as found on your actual website.
This way I will get access to any updates you might have made.
Best regards,
Geoff B.