Please do not use root to build this system.
Step 1: mkdir openwrt
Step 2: cd openwrt
Step 3: svn co svn://svn.openwrt.org/openwrt/trunk
Step 4: run script to update all the latest pakage on system.
./scripts/feeds update -a
Step 5: sudo apt-get install libncurses5-dev ncurses-term zlib1g-dev gawk bison flex autoconf