While the current Catechism came out after your ordination, the basic principles were in place long before it:

http://www.vatican.va/archive/ccc_css/archive/catechism/p3s1c3a1.htm

1979 The natural law is immutable, permanent throughout history. The rules that express it remain substantially valid. It is a necessary foundation for the erection of moral rules and civil law.

1980 The Old Law is the first stage of revealed law. Its moral prescriptions are summed up in the Ten Commandments.

It is the cultic laws of the Old Testament that were superseded. We do not engage in ritual cleansing, Temple sacrifice, or observe kosher.

In addition Jesus superseded Mosaic marriage law in part.