To create an Employee account, just click on "Add new employee".
The "Add new employee" button takes you to the employee creation form.
It has some settings:
First name and Last name: The name does not appear to customers, but is very helpful when you need to know who did what on your shop.
Email address: This is the employee's back office login ID. If allowed to, the employee will receive customer emails and PrestaShop notifications on this address.
Password: Try your best to not make it obvious. You would not want unknown people to be able to guess it.
Default page: You can decide which page the user sees right after logging in. This could be the Stats page for Administrators, or the Orders page for salespersons.
Language: The user's default language, since your business might be done in English, but your logisticians might be from another country. Make sure to add the necessary languages on the "Languages" page under the "Localization" menu.
Active: You can temporarily and definitively disable an account. This enables you to create temporary accounts, for instance when you need help during the holidays or the shopping season.
Permission profile: You must select the profile you want to assign to your employee.