The preferred way to install root is from source and with *cmake*. The installation from source might not be necessary but is necessary for example if extra libraries (such as GQt for the FACT++ GUI) are required.

Forst download the source tar-ball from ​http://root.cern.ch (The version in the following is just an example, names and places are just a suggestions)

[0] tar xvfz root_v6.14.04.source.tar.gz  # Extract the tar file 
[1] mv root-6.14.04 root-6.14.04-src      # Rename the source diretory (for convenience)
[2] mkdir root-6.14.04                    # Create a build directory
[3] cd root-6.14.04                       # Change into the build directory
[4] cmake ../root-6.14.04-src             # Create the build environment
[5] make                                  # Make root
[6] rm -rf ../root-6.14.04-src            # Now the source can safely be removed
[7] . bin/thisroot.sh                     # Properly setup your environment

You might want to call cmake to setup the build environment with a different (e.g. faster) compiler like clang:

[4] cmake -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ ../root-6.14.04-src

To force the compilation of the GQt module

[4] cmake -Dqt=ON ../root-6.14.04-src