General build instructions for KDE packages can be found at 
  http://techbase.kde.org/Getting_Started/Build/KDE4
but these pages are currently being rewritten.

Specific build instructions for Umbrello can be found at 
  http://umbrello.kde.org/installation.php

In short, here is how to build current git master on Linux :
  git clone git://anongit.kde.org/umbrello  
  cd umbrello
  mkdir build
  cd build
  cmake -DCMAKE_INSTALL_PREFIX=$HOME/umbrello -DCMAKE_BUILD_TYPE=Debug  ../

