Use yarn new <package-name> to create a new package.
Also, once a package has been created, in order for publishing to be possible, it also needs an explicit "private": false in its package.json in order to be publisheable by lerna publish.
Helper command yarn wizard will pop up a menu with useful things you can do, you have even more available options using yarn lerna --help.
Please remember to replace this readme with something more project centered! Cheers~