Go to ATO>Style WIDGETS>Widget Title Box and add whatever code you want. If you want the background to be red you can just put
HTML Code:
background-color:red;
You can of course use hex numbers for other colors. If you want the text to be red use
If you want the border red use
HTML Code:
border:1px solid red;
For the top rounded corners I would guess you could use
HTML Code:
-moz-border-radius-topright:10px;
-moz-border-radius-topleft:10px;
-khtml-border-radius-topright: 10px;
-khtml-border-radius-topleft: 10px;
-webkit-border-radius-topright:10px;
-webkit-border-radius-topleft:10px;
border-radius-topright: 10px;
border-radius-topleft: 10px;
All the extra code here is because different browsers use different implementations of the CSS for rounded corners. You can change the 10px to different values for a smaller or larger radius.