How to change the color of the widget headers from black with white text to something else?

Hello Tracey ! 
– To change the color of the widget headers, you can add the following code to the Header Code (Dashboard > Appearance > Customize > General Setting:

<style>
#secondary .widget.latest-news .widget-title:before {
    border-top-color: #...;
}
#secondary .widget.latest-news .widget-title {
    background: #...;
    border-top-color:.... ;
    border-bottom-color:....;
}
.accordion .accordion-heading a {
    background: #...;
    color:#...;
}
.accordion .accordion-heading a.active {
    background: #...;
    color: #...!important;
}
</style>

– The DW Focus:tabs widget, you can change color widget in the Dashboard > Appearance > Customize > Style Selector.
Hope this helps !