How to write prog. in GCC

Hello friends

Up till now i have used Keil compiler to write code for LPC2148

Now i want to write code in GCC compiler

I never tried GCC compiler to write code for LPC2148

Is there any source from where I can learn on my own.

What tool chain i require to compile code in GCC

I am not looking for complex code right now

Some simple code.. and step by step procedure to compile the code

I have lpc2148 kit to test the code

please help me!!!!!!