How can I get the first value of several related tables?

The query that you sample is correct but incomplete, you should try this way

SELECT pr.nombre AS 'nombrePrograma',pr.id 
FROM programas pr
JOIN cursos ON pr.id = cursos.programa_id 
ORDER BY pr.nombre DESC
LIMIT 1

By using ORDER BY you are indicating that from the results dataset you order it by the column pr.nombre and indicating it so DESC will sort it in this way

If I have these records

Nombre
______
Alfredo
Daniel
Julio
Pedro
Beto

THE RESULT SHOULD BE LIKE THIS

Nombre
______
Alfredo
Beto
Daniel
Julio
Pedro

Now if you want the order to be made from the most recent record, then use the column that you have registered by id; I would do it this way

SELECT pr.nombre AS 'nombrePrograma',pr.id 
FROM programas pr
JOIN cursos ON pr.id = cursos.programa_id 
ORDER BY pr.id DESC
LIMIT 1

  

When handling sorting by the column% co_of% that is or should be   a primary key will return the last record made and the   combine it with id will only show a final record