Are you required to use windows forms? If you can, break free of the the '90s and join the '10s.
Don't worry, my first article on here was forms using MDI (at first), and that was around 2005.
No matter... who owns who? Does the Panel own the MenuStrip? Is the MenuStrip created in another class?
Here's a suggestion without more details (BTW I read your code):
http://stackoverflow.com/questions/14126356/setting-mdi-child-transparency-possible-vb-net[
^]
"make MenuStrip and Panels transparent"... Far too broad to get a proper answer. This isn't SO, but please be more specific and you will get a more specific answer.
I hope the link or my broad suggestion gives you some direction.
If you need more assistance, please don't hesitate to ask. Just make your question more specific :)