Basically add a new panel to your current layout.
you will end up with this:
Thing here is doing the correct anchoring, so this settings should work:
-Picturebox
: Anchor:Top, Left, Right
. Just adjust size to your needs.
-pnlHeader
: Anchor Top, Left, Right
. Just adjust size to your needs.
-pnlMenuContainer
(Orange): Anchor Top, Left, Right.
It should be of same Height of contained MenuBar, because it is just for placing the menubar.
-MenuStrip
(MenuBar in img): Dock Top
(or Bottom).
With this layout PictureBox and MenuStrip increase their size as you make your form wider. Actually for the MenuStrip, the panel that contains it is the one that increase it size but as your menuStrip is docked it gets bigger too. Same for the inverse (Making it smaller).
I must apologize in advance for any kind of grammar or spelling error.
Best of luck,