For the best results, use the latest version of Cura LulzBot Edition. Legacy Cura LulzBot Edition is still available, but will no longer be updated. For the latest and greatest see https://www.lulzbot.com/cura
Please report any Issues With Cura LulzBot Edition here: https://code.alephobjects.com/project/board/10/
Cura is a Free Software program that both prepares your files for printing (by converting your model into GCODE), and also allows you to control the operation of your LulzBot 3D printer.