1. If you want to change background color, please edit theme’s style.css file and around line 2435 find this part:
.headerrow { background: rgba(237,32,32,.85); min-height: 113px; }
Now, change the background values. Color is in RGB format and the forth value is for transparency (0-1).
2. If you want to change background image, please make your image JPG image dimensions 2437 x 113 px and name it as sky_bg.jpg. Upload this image to /wp-content/themes/wp_hot_churchly/images/custom folder using FTP. If you are using style 2 or 3 for this theme, name image as sky_bg2.jpg or sky_bg3.jpg.