you should follow doc/readme-qt.rst if building QT frontend
if using ubuntu >=12.04
apt-get install qt4-qmake libqt4-dev build-essential libboost-dev libboost-system-dev \
libboost-filesystem-dev libboost-program-options-dev libboost-thread-dev \
libssl-dev libdb++-dev libminiupnpc-dev
then
cmake && make -j <cores number + 1>
for eg. core i3 with 2 cores and hyper threading: make -j 5