How do I convert a Windows .bat job to a LibreOffice job?

This job is run on the black command window. Like this: C:\MYJob>runthejob myrun

Where MYJob is the file and runthejob.bat is the .bat to run in Windows the program myrun.

More information is needed. What kind of thing is being run, and under what circumstances does it get run? What is a “LibreOffice job” – are you asking about LibreOffice macros? Also, the question states that MYJob is the file, but “C:\MYJob” suggests that it is the directory instead.

Maybe you want to do something like this example macro.

Sub RunCommand
    sTerminal = "cmd.exe /C"
    sCommand = "echo " &  Now() & "  Written from LibreOffice." &_
        " >> ""%USERPROFILE%/Desktop/time.txt"""
    Shell(sTerminal & " " & sCommand)
End Sub