Designing a bootloader to take application code (led blinking code) from SD/MMC card using SPI and burn in flash of LPC1768 and execute that application code on reset.
In addition to rkopsch's suggestion, you should be looking to NXP for specific examples & assistance regarding their products.
https://www.nxp.com/products/processors-and-microcontrollers/arm-microcontrollers/general-purpose-mcus/lpc1700-cortex-m3:MC_1403790745385#/
Select your specific chip variant for tools, documentation, etc, etc, ...
There's also mbed:
https://os.mbed.com/platforms/mbed-LPC1768/
https://www.nxp.com/products/processors-and-microcontrollers/arm-microcontrollers/general-purpose-mcus/lpc1700-cortex-m3/arm-mbed-lpc1768-board:OM11043