The layers: Constitution, Acts, Decrees, Rules
Below the Constitution are Acts passed by the National Assembly. Details an Act delegates are set by Presidential Decrees (enforcement decrees) and by Prime Minister's or Ministry ordinances (enforcement rules). So when an Act says 'as prescribed by Presidential Decree', the actual standard is in the decree. The statute book lists each type separately so you can follow these layers.
Reading an article: article, paragraph, subparagraph, item
An article (Article 1) divides into paragraphs (1), paragraphs into subparagraphs (1.), and subparagraphs into items (a). An article such as 'Article 3-2' was inserted between existing numbers by an amendment. References chain these units, as in 'Article 3 (1) 2'.
Check the effective date and the addenda
Laws change often, and the date a law takes effect often differs from the date it was promulgated. When and how it applies is set out in the addenda, so for any date-sensitive question check the addenda and the reference date first.