When Presenting a powerpoint I tried to minimize the PP and go online to demo. The site comes up on my Laptop but not on the projection. That only displays the home screen.
You can drag the title bar of the browser window over to the other display. If you open the System Preferences > Displays, then Arrangement tab, you can see where the projector's display is in relation to the laptop display. The main display (typically the laptop's) has a tiny white menu bar depicted in this Arrangement window.
Just click-drag the window in the direction of the second display and it will pop over to the projector.
You can also change the arrangement if it helps. Put the projector above, below, left/right of your laptop display.