[Deque]

I split the posts to their own topic.

@HattityHat: A language is just a language, i.e. something you use to communicate. That is true for spoken languages as well as programming languages. A language consists of syntax, (key-)words and semantics. You can not download it.
So let me rephrase your question to: What do I have to download to create C++ programs?

1. Advice: Use google, it is your best friend.
2. Advice: Read this: http://www.hackcommunity.com/Thread-How-...or-dummies
3. Advice: Read this: http://www.cplusplus.com/doc/tutorial/

What is a compiler? In this case it is translator for a programming language to machine code (the language that the computer understands).
More general it is a translator for higher level language to a lower level language.