My First Blind Xss

Hello Guys I Hope All of you are fine

A NEW E-Commerce Website Have been published and his owner is my friend so he asked me to do some tests so i go to xsshunter.com/ and copy the img payload and puts it in any parameter i have seen

then i saw contact us form so i decided to send the payloads throw it

i filled every thing by payloads then after 3 days its fired in admin panel and i take it over