Hello,

01. Please add the following Custom CSS code to Theme Settings > Custom CSS > Global Custom CSS. change the code as per your requirements.

.whb-header-bottom {
    background: linear-gradient(to left, #142def, #190d04);
}

02. Navigate to WoodMart > Header Builder > Edit Current Header > Add the Categories elements and choose the menu.

For more details follow this guide:
https://xtemos.com/docs-topic/product-category-menu/

Best Regards.