You can add these CSS blocks to your Thesis -> Custom CSS screen

1. Change Secondary Nav Static Colors

.secondary-nav a, .secondary-nav .current ul a, .secondary-nav .current-cat ul a, .secondary-nav .current-menu-item ul a {background: #000; color: #fff;}

2. Change Secondary Nav Highlights

.secondary-nav a:hover, .secondary-nav .current ul a:hover, .secondary-nav .current-cat ul a:hover, .secondary-nav .current-parent a:hover, .secondary-nav .current-menu-item ul a:hover, .secondary-nav .current-menu-ancestor a:hover {background: #000; color: #fff;}

3. Remove the background color from headers on post titles

.top-posts .featuredpost h2 a, h2.headline a {background: transparent; color: #454545; box-shadow: none;}
.top-posts .featuredpost h2 a:hover, h2.headline a:hover {background: transparent; color: #CC0000; box-shadow: none;}
.top-posts .featuredpost img, .content .post_box img.wp-post-image {margin-bottom: 5px;}

4. Hide the featured slider meta data (posted by, date, comment count)

#posts_slider .meta-item {display: none;}

5. Change the footer area background color

#footer-widgets {background-color: #fff; border-top: 10px solid #fff;}

6. Hide elements from the tabbed widget
You can remove items by adding this CSS, change the number to the number of the tab you want to hide, i.e:

/* Hide the comments tab */
ul#tab-items li:nth-child(3) {
 display:none;
}

7. Hide the top menu area

You can hide the top menu by creating a new menu under Appearance -> Menus and just add one menu item to it with a CSS class of "hidden" (http://cl.ly/image/0R0y1V41453u).

If you don't see the CSS classes, hit the screen options tab on the top right to make sure it's checked off.

Then add this CSS to your Custom CSS:

#nav {display: none;}
.hidden {display: none !important;}

Finally under Thesis -> Skin Content -> Primary Navigation set the drop down to the menu you just created above.

8. Increase sub menu drop down width and/or decrease font

.secondary-nav li li a {
    width: 200px; 
    font-size: 8px;
}