Invasive plant species disrupt native ecosystems and cause economic harm to public lands. In this report, an example of applying the Detection of Early Season Invasives software to mapping cheatgrass infestations is given. A discussion of each step of the DESI process is given, including selection of Landsat images. Tutorial data, covering a semi-arid area in southern Utah, are distributed with this report. Tips on deriving the inputs required to run DESI are provided. An approach for evaluating and adjusting detection parameters by examining interim products of DESI is discussed.