There is a section in the docs that shows COBOL and C# equivalencies for common programming constructs that you can find here:

There is also a video that covers some of this material called the Fundamentals of using Visual COBOL and .NET which you can find as part of the COBOL Rocks Tech Cast series that we did last year.

This is what the converted example would look like:

     $set ilusing"System.IO"
     $set ilusing"System.IO.Compression"
      program-id. Program1 as "testzipfile.Program1".
      procedure division.

          declare startPath as string = "c:\\example\\start"
          declare zipPath as string = "c:\\example\\result.zip"
          declare extractPath as string = "c:\\example\\extract"

          invoke type ZipFile::CreateFromDirectory(startPath, zipPath, type CompressionLevel::Fastest, true)
          invoke type ZipFile::ExtractToDirectory(zipPath, extractPath)

          goback.