Current iTunes has no "toolbars".
To authorize your computer, try the applicable one of these:
• iTunes 11: use iTunes > Store > Authorize This Computer… menu command
• iTunes 10 or older, search iTunes > Help menu for "Authorize This Computer…"
• If no iTunes menu at top of Mac's display, restart Mac, launch iTunes.
• If problem still exists after trying the above, download and re-intall iTunes.