Questions About Script Task

I'm following the example here.

http://www.singhvikash.in/2013/05/ssis-how-to-loop-through-multiple-files.html

I think I have everything setup right, but something is not working here.  I followed all the steps, and for the scripting part, I did this:

Project > Add New Item > Class

I have a red squiggle lined under these two lines of code:

System.AddIn.AddIn

(int)ScriptResults.Success;

Here's an image.

I've done a bit of C# dev work, but not much really.  Also, I'm pretty new to SSIS.

Thanks, in advance, for the help.

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