The link embedded will take you to the download page for the MCUXpresso IDE, a customized version of Eclipse maintained by the microcontroller manufacturer NXP. You will need to make an account to download the IDE. (I am looking for open source alternatives passively.) Follow their instructions for getting the IDE up and running for your system.

The link embedded will take you to a web page where you will need navigate to a link saying "Select Developement Board". After logging in with your NXP account, you can build an SDK for the LPC804 development board. This will contain examples. Follow the instructions from the download to get the SDK integrated with the IDE.