Where to start with a STM32F4DISCOVERY
I don't think that CodeSourcery is supported by ST, use a toolchain that is.

Documentation and projects (including IO_Toggle for flashing LEDS) are here:

http://www.st.com/internet/evalboard/product/252419.jsp

You might find the Atollic tools easiest to use. I had the LEDs flashing a few minutes after I received the kit.

ST  has a support forum for that board here:

https://my.st.com/public/STe2ecommunities/mcu/Lists/STM32F4DISCOVERY/AllItems.aspx