This will show the list of students in the course. You may select the students to include on the invoice in two ways

1) check off individual students listed ( using the checkbox on the right)

2) Use the Select All button above the checkbox to select ALL the students

You will see this dialog, click yes to select all the students.

(you may also use the select all button to de-select all the students, the button "toggles" the selection of selected students)

Search for  the company to invoice:

Type a partial name until you see the name of the company in the portal below

Click the Select Company Here button next to the desired company

Invoice Details should now show the company name and the students from the course to bill on the invoice

Click the Create Invoice button

Follow the normal process of address selection to complete the invoice.