How to add payment icons in footer

Site URL: https://luluthelabel.com/

Hello, 

How do I add or link these payment icons in the footer of my website? 

I have noticed a lot of websites have these and I would like to add this on mine as it's useful info for the customer. Thank you.

Add to Design > Custom CSS

/* footer payment icons */
.Footer-middle:before {
    content: "";
    background-image: url(https://content.invisioncic.com/p289038/monthly_2021_06/1071171527_Screenshot2021-06-06at22_58_19.png.98f2c5c2c295a67a4137384275a8b19a.png);
    background-size: contain;
    background-repeat: no-repeat;
    background-position: center center;
    width: 100%;
    height: 50px;
    display: block;
}