Steps to build your linux images on buildroot

Extract your buidroot_xxx_.tar.gz
cd into the buildroot directory
issue commands:
make distclean
make i386_defconfig
(if you are building image for i386 - for other processors - run 'make help' get to know what to use)
make menuconfig
(Now set whatever is required for your build. In the defconfig file name for the 'Kernel' give suffix as i386)
make