Solicitor theme comes with mega menu creation plugin built in.
Follow this support topic for more info: http://support.imithemes.com/forums/topic/how-to-create-a-mega-menu/
Here is a video describing the process of creating a Mega Menu.
Here are some steps to show you how to enable and use Mega Menu.
Step 1 : Navigate to Appearance > Menus and click Screen Options on the top right corner. Check the Mega Menu checkbox to enable it.
Step 2 : Check the “Create Column” checkbox and then click “Add to Menu” to add a new column for a Mega Menu.
Always make sure that a mega menu column is added as a sub menu item to a parent menu item.
Step 3 : Drag the Mega Menu to a parent menu item and check “Enable Mega Menu” checkbox.
Step 4 : Customize menu heading in the “Navigation Label” and add any icon to the title.
Step 5 : Choose a post type from the dropdown ( post, page, product, projects, speaker, sermon, services, wr_cf_post_type, staff )
Step 6 : To show some specific page, post links then just leave the dropdown selection to default “Select Post Type” and enter the ids of the pages, posts in the text field provided