I Cant Get To TWRP Recovery HELP !!!

hello guys i have a LG-G2 Sprint i flashd it and i found SuperSU pre-installed :confused::confused: i think that that well change something also whene i try to root my phone it dont work help me guys i want to install a costom rom but dont know what to do

from xda-developers http://ift.tt/1Xik146
via IFTTT