You may use this link{https://karimmd.github.io/post/tutorial/ns3_installation/} or follow the instructions below: 

$ sudo apt update

$ sudo apt install g++ python3 cmake ninja-build git gir1.2-goocanvas-2.0 python3-gi python3-gi-cairo python3-pygraphviz gir1.2-gtk-3.0 ipython3 tcpdump wireshark sqlite sqlite3 libsqlite3-dev qtbase5-dev qtchooser qt5-qmake qtbase5-dev-tools openmpi-bin openmpi-common openmpi-doc libopenmpi-dev doxygen graphviz imagemagick python3-sphinx dia imagemagick texlive dvipng latexmk texlive-extra-utils texlive-latex-extra texlive-font-utils libeigen3-dev gsl-bin libgsl-dev libgslcblas0 libxml2 libxml2-dev libgtk-3-dev lxc-utils lxc-templates vtun uml-utilities ebtables bridge-utils libxml2 libxml2-dev libboost-all-dev 

Now unzip or untar the ns-allinone-3.38.tar.bz2 to the home folder.

Now we need to install it by running the command 

Open a new terminal 

$ cd ns-allinone-3.38/

$ ./build.py --enable-examples --enable-tests

$ ./waf configure --enable-examples  # Build ns-3 installation

$ ./waf # to check whether installation was a success

$ ./waf --run hello-simulator

Example for Execution of Programs: https://networksimulationtools.com/how-to-install-netanim-in-ns3/ 

Click Here