Button at bottom far left is the Start button they're talking about.

If it's not visible, and if it won't let you drag the bar into view:

Control-Escape will bring up the Start menu, and on it you can select Settings, Taskbar and Start Menu Settings, where you should be able to turn off a "hide taskbar" and/or unlock the taskbar so it can be dragged back into view.

Once you get the taskbar where you want it, I'd suggest right-click on any blank space on the taskbar and click "lock taskbar."

John