Installing gcc on windows 7 could be done easily by downloading Dev-C++ or devcpp. Dev-C++ or devcpp is featured Integrated Development Environment (IDE) for the C/C++ programming language. It uses Mingw port of GCC (GNU Compiler Collection) as it’s compiler. Dev-C++ can also be used in combination with Cygwin or any other GCC based compiler.

you can use this devcpp to compile and run your C or C++ program, but if you want to experience manual compilation using cmd and gcc, you need to modify you windows path, so that you can run gcc command everywhere on you command prompt. Just follow these steps

1. Download Dev-C++
2. Install Dev-C++, for easy process just do the “next” and “next”, you don’t need to configure the installation location
3. After you finish the installation you need to modify windows path to do this first you need to click the start button on windows 7.
4. Right click on “Computer” (above control panel) Menu choose properties
5. Choose advanced system setting (located right above the screen). System properties window will appear.
6. Choose advanced on tab menu, and click environment variables.
7.  On user varibles click new
for variable name write PATH
for variable value write C:\Dev-Cpp\bin;

8. Now you can compile your program anywhere using command prompt
just run gcc programname.c -o programname

to download DevCpp you can go
here