Can you tell us exactly what you did on epizy to create your website? Maybe we can help figure out where it went wrong.
You might want to set up a development environment on you local machine instead of editing the active website directly. That's safer and won't break the website for your users when you make new things and test them (and some of those new things inevitably create errors).
You can develop and test the code on your machine and then upload it to your hosting service when you're done.
Xampp is a good php environment that's pretty easy to set up on windows and Mac (also Linux but I assume you're not using a Linux os), for example. There are also other environments if you'd like a more lightweight one, but some are difficult to set up if you haven't done such a setup before.
If you want pets / adopts that grow over time and/or through clicks you will have to write the code for that yourself or copy/use it from free sources (like mysidia or kitto). Both of those give you a good basis imho