how to change border color of interst box

Could be wrong, but I think it's something like:

<style>

    .table-section .heading{

    border-radius: 25px 25px 25px 25px !important; (THIS CHANGES THE THICKNESS/SIZE OF THE BORDER IF YOU WANT) 

    text-align:center; 

    background-color: (INSERT COLOR HERE) !important;

    background-image: url('URL');

    background-repeat: repeat;

    background-position: center;} 

</style>