Paintbrush options normally found at the bottom left corner while in edit mode.
Are you asking about the "Paint Brush" in the toolbar in iPhoto on your iPod or iPad? That brush is only available in iPhoto on IOS, not in iPhoto '11 on your mac. Or asking about the "Retouch" brush in iPhoto '11? That is in the "Quick Fixes" tab.
Your profile signature is somewhat contradictory - iPhoto '11 does not run on IOS devices.