follow the steps from here

lb-set-platform x86_64-slc6-gcc49-opt

lb-dev Gauss/v49r17

cd ./GaussDev_v49r17

git lb-clone-pkg Gen/DecFiles

make install

#check the event type number, Wuv is 42311003 in Wmass analysis 2016, find the .dec in Gen/DecFiles/dkfiles

#it is W_munumu=10GeV.dec

cd Gen/DecFiles/cmt

./decparser.sh ../dkfiles/W_munumu=10GeV.dec