I stated with the wget function:

    wget https://github.com/broadinstitute/gatk/releases/download/4.0.2.1/gatk-4.0.2.1.zip

I think my problem deals with the gatk-4.0.2.1.zip file.  After I unzip the file I can view the contents; however, no where do I see the **GenomeAnalysisTK.jar** file?  I only see the two gatk-package jar files - listed below.  

gatk-package-4.0.2.1-spark.jar and gatk-package-4.0.2.1-local.jar

I'm expecting to find the GenomeAnalysisTK.jar file.

Perhaps my instructions are a bit old?

Now there is a wrapper script called `gatk`, so you just have to call it. Try `gatk` with no parameters, or:

    gatk --list           Print the list of available tools
    gatk Tool --help      Print help on a particular tool

The wrapper is a Python script:

    #!/usr/bin/env python
    #
    # Launcher script for GATK tools. Delegates to java -jar, spark-submit, or gcloud as appropriate,
    # and sets many important Spark and htsjdk properties before launch.