Excel - insert column and row

I have Office Mac and I cannot get the insert column and insert row toolbar buttons to work.

They are shaded out or lighter than the rest of the icons in the toolbar.

I have gone through the preferences and tried all other sorts of views, options and such and cannot figure out how to do this.

It quite challenging because I am used to using the toolbar from my computer at work and it is hard to break that habit.

Please let me know if you have any ideas on how to get the insert column and row buttons to work.

Thanks,