Before you sign up for the DELE exam, check if the registration period is open. Be careful, you have to register in advance, as registrations usually close a month and a half before the exam. To see the exam dates and closing dates for registrations, click hither.

You can also check here, in which center to enroll: https://examenes.cervantes.es/es/dele/donde

If you are going to take the DELE outside of Spain, you will have to sign up for the exam at the center or on its website. They'll make you fill out a form like this: https://examenes.cervantes.es/sites/default/files/formulario_inscripcion_dele_2022.pdf

If you do the DELE within Spain, you can register here: https://examenes.cervantes.es/es/user/register