You can only register online. When you select the desired course, you can press the orange button “Register”. Then you will see all the possible schedules, where you will have to choose the one you wish to follow.
After this the registration is added to the basket, in the right top corner. Click on the basket to continue to the checkout. There you have to fill in multiple details and if you don't have it yet, create a portal account. After this you can select the payment option.
You will always receive a confirmation e-mail when the registrering is done.
FYI : If you want to apply for a Dutch course with a DUO loan there is a different application procedure. You will first need an intake if it's your first course, you can schedule an intake interview here.