C++ makefile and g++

#include < iostream >
using namespace std;

int main(void) {
cout << "welcome to www.fruitfruit.com" << endl ;
cout << "MinGW test" << endl;
return 0;
}
//~ set environment variables:
//~ C_INCLUDE_PATH = C:\MinGW\include
//~ CPLUS_INCLUDE_PATH = C:\mingw\include\c++\3.4.4;C:\mingw\include\c++\3.4.4\mingw32;C:\mingw\include\c++\3.4.4\backward;C:\mingw\include
//~ LIBRARY_PATH = C:\MinGW\lib
//~ PATH = C:\mingw\bin
//~ build command line:
//~ D:\test>g++ main.cpp -O3 -o hello
//~ makefile:
//~ all:
//~ g++ test1.cpp -g -o run