Running a from class inside your JAR file load.jar is possible via
java -jar load.jar
When doing so, you have to define the application entry point. Usually this is done by providing a manifest file that contains the Main-Class tag. For documentation and examples have a look at this page.
The argument load=2 can be supplied like in a normal Java applications:
java -jar load.jar load=2
Having also the current directory contained in the classpath, required to also make use of the Class-Path tag. See here for more information.