UPDATE June 25th: ndn-cxx MUST be compiled as a shared library now, the tutorial is now reflecting this change by executing ./waf configure --enable-shared --disable-static for ndn-cxx

First of all: follow the tutorial provided here:
Second: If you feel comfortable enough, you can copy and paste the commands from this how-to, which will generate the following directory structure:

~/ndnSIM
~/ndnSIM/BRITE
~/ndnSIM/ndn-cxx
~/ndnSIM/ns-3

Third: This tutorial comes without warranty. Double check every command before you copy/paste it to your commandline.

Commands for Ubuntu 14.04:

# install pre-requesits for ndn-cxx, ns-3, etc...
sudo apt-get install git
sudo apt-get install python-dev python-pygraphviz python-kiwi
sudo apt-get install python-pygoocanvas python-gnome2
sudo apt-get install python-rsvg ipython
sudo apt-get install build-essential
sudo apt-get install libsqlite3-dev libcrypto++-dev
sudo apt-get install libboost-all-dev

# build ns-3/ndnSIM with brite
cd ns-3
./waf configure -d optimized --with-brite=/home/$USER/ndnSIM/BRITE
./waf
sudo ./waf install


Ideally, this outputs:

Modules built:
antenna aodv applications
bridge brite (no Python) buildings
config-store core csma
csma-layout dsdv dsr
emu energy fd-net-device
flow-monitor internet lr-wpan
lte mesh mobility
mpi ndnSIM netanim (no Python)
network nix-vector-routing olsr
point-to-point point-to-point-layout propagation
sixlowpan spectrum stats
tap-bridge test (no Python) topology-read
uan virtual-net-device visualizer
wave wifi wimax

Modules not built (see ns-3 tutorial for explanation):
click openflow


Done!