P0456 - Is my gas tank broken?

Hi--

First off, I'll say that I'm not a "car person" and may not be using correct terminology below. But I will include a photo so you can see what I'm talking about. I'm curious if the opening to the gas tank (the part you can see and insert the gas pump nozzle into to fill up the tank) looks damaged to you.

Here are all the details:

I'm getting error code P0456 - EVAP System Leak Detected (very small leak).

I've bought eight different gas tank caps from Amazon and tried replacing the gas tank cap. None of them succeeded in getting the "check engine" light to turn off.

I then did a closer visual inspection of the gas tank and saw that the black ring around it might be broken? This is what I saw:



I noticed that there's a black ring circling around the opening to the gas tank (indicated by the red arrow). But it appears that maybe some of it has broken off? I can see some metal (indicated by the yellow arrow).

Two related questions:

1. Is this a sign of damage/could it possibly be the reason for error code P0456?

2. If so, is this something that I (someone with basically no knowledge of cars) could fix myself? Or would I be better off taking it to a mechanic?

Thank you for your help,
ak