You're going too nervous.
Relax and ask sensed questions.
Now about answering the questions you made:
I know about directX and STL and stuff, but what about unity? Does that use C++? |
As of wikipedia, it uses:
C++
C#
JavaScript
Boo
And what C++ files do I use? |
Depends on which engine you pick.
Every engine will make you download some files (Header/Library/DLL, or Header/Library, or Header/Source).
Then, you must look at dedicated tutorials or documentation.
Do I use <iostream> , or cstdlib? |
You don't use either one.
You should stick to what your engine uses.
Eventually, you can still use iostream for std::string, etc.
ALso, should I learn java? |
Makes no sense.
You are programming in C++, you only need to learn C++.
Or should I program windows first? |
Makes no
grammatical sense.
What did you mean?