Layering objects and Widgets help

Hey so I have two questions, both will refer to the website here: https://www.purduesolar.org/new/

1) As you can see, when you hover over the menu, the second level menu pops up, but is overshadowed by the slider. How can I make it so the menu is always on top?

2) I’m using a theme called Mystique, and they edit widgets in the sidebar using only the php file, instead of the Widgets option underneath Appearance. I want to add a widget, a text widget, just to add some images on the sidebar (sponsors), how do I go about this?

Here is the code from sidebar.php

[Code moderated as per the Forum Rules. Please use the pastebin]

Thanks for the help!