Updating the header background color in the Echo theme is quite easy.
Open your /templates/Echo/css/echo.css file:
Find:
/*-----------------------------------------------------------------------------------*/
/* 3.Header (Navigation, Search, etc.)
/*-----------------------------------------------------------------------------------*/
header.pm-top-head {
display: table;
position: fixed;
background: #FFF;
border-bottom: 1px solid #e8e8e8;
Replace both #FFF and #e8e8e8 with your desired color code.