This is Bible study correspondence ministry, which uses books and pdfs that may be downloaded off the internet. I think they have some questions and answers that people need to answer regarding the books and pdfs.
The books are around 16 dollars each and the pdfs of the books are around 8 dollars each. I counted around 23 books or courses on the website. Please look for the word Cursos on the website to see the courses. After you finish the Bible studies and take the tests, you will qualify to receive a diploma.
The website is not complete. You will probably have to call or email the ministry for more information.