permanently display my imac toolbar bar

I think you are referring to what is called the Dock, to have it permanently visible go to System Preferences>Dock and uncheck Automatically Hide and Show the Dock.

If however you are perhaps referring to the Menubar at the top of the screen this automatically disappears when you are in Full Screen Mode, if you move your cursor to the top of the screen it will become visible. To have it permanently displayed come out of Full Screen Mode, move your cursor to the top of the screen your menubar will appear, click on the green button.

Is it your menu bar along the top of the screen. If you have your browser and document editing app set to go Full Screen, it will use the entire screen, including the top edge of the screen.

If it is Full Screen mode, try Command-Control-F to switch the application out of Full Screen mode (or if you are not in Full Screen mode, Command-Control-F will put the app into Full Screen mode)

Just in case you are referring to the Dock rather than a toolbar:

Apple menu > System Preferences > Dock > remove checkmark in front of "Automatically hide and show the Dock"

I can't remember if Yosemite had this option, but check System Preferences/General to see if Automatically hide and show the menu bar is checked.

Not applicable to Yosemite, came in with El Capitan.