You have two options to invite new users to your Q. team.
Click on the big pink "+" button on the left and select "Invite Users". Now a pop-up window opens where you can type in the email address, the name and select a user role. Afterwards you click on the 'Invite' button and Q. sends the invitation to all your new users via email.
The user overview is the second way to invite new users into your Q. Click in the sidebar menu on "Users" to go to the user overview. Here you need to click on the pink '+' button to open the invitation pop-up window. As above, you can also specify the email address, the name and the user role.
Don't forget to create roles and assign user to them. If you have not determined any user roles yet, you can find help to do it here: Create new roles