Can't add markers

Hi there, newbie using Logic Pro X v10.5.1 on a mac mini and I've fallen at the first hurdle! I've imported an mp3 file and I'm trying to add markers.

I've tried adding the marker list to the global list but it isn't available as an option. Also tried a keyboard shortcut and it's not working either.

It's such a fundamental thing I'm so frustrated :-(

Help!

Thanks :-)