There are several methods or languages to program with depending on how you want the programs to run. Older ones like C or C++ run on the client (your) machine where ones like HTML/PHP, Oracle Forms run on the server. Oracle Forms is somewhat special as it is mainly for running against their databases. JAVA is a bit of both as the code can reside on a server and "jar" files are sent to the client usually and the associated libraries are also sent.
If you have a few minutes of spare time, here are some links to explain the whys and such of the various languages.
JAVA
1. How Java Works
HTML/PHP
HowStuffWorks "How HTML5 Works"
Oracle Forms
Oracle Forms - Wikipedia, the free encyclopedia
C++
HowStuffWorks "How C Programming Works"