Stellar template offers only one type of menu, horizontal, in Header area. So far only there you can use MegaMenu features.

You can also disable default Predefined Header and build your own. More about in Helix Ultimate Manual.

How to enable Page title in articles

1.  In menu item, enable Page Title and set bg color or image
2. Then use below custom CSS code:

.com-content.view-article #sp-title {display: block;}
.view-article #sp-title .container { max-width: 100%; padding: 0;}
.sp-page-title h3 { font-size:16px;text-align: center;}
.view-article .sp-page-title {padding: 150px 0 135px;}