In HEP, the principle computational language was, for several decades, Fortran. In the early 1990s OO (Object Oriented) languages such a C++ and Java began to make an impact and today C++ dominates in off-line applications such as Monte Carlo, Event Reconstruction and Physics Analysis. However Fortran still plays a significant part in some of the older experiments, particularly those that are well into the data taking stage.
We won't attempt to teach these languages here but the following are useful resources:-