So, you want to contact the author of the tutorial! Why exactly do you want to do that?
I'm always glad to help out when people have trouble understanding the tutorial, or can't get one particular example to work. However, instead of sending the question directly to me, please consider sending it to the Globus-Discuss mailing list (subscription information here), where all the GT3 community hangs out. That way, a lot more people will be able to help you out, and we'll all benefit from the replies to your question.
A word to the wise: if you post a question to Globus-Discuss make sure to include as much information as possible about the problem you're facing. Short and vague e-mails that simply state "I have a problem in example FOO, the error message says something about BAR. What am I doing wrong???" usually get no response, or take several iterations to be solved. When available, send along stack traces, snippets of code related to your problem, etc. If you have time, take a moment to read the (excellent) How To Ask Questions The Smart Way by Eric S. Raymond, which explains how to ask questions in public forums, such as mailing lists.
Please report it directly to me by e-mail: borja AT borjanet DOT com
Constructive criticism is always welcome and, in fact, many readers have helped shape the actual contents of the tutorial through their suggestions and comments. I'm always interested in knowing if readers find the contents useful, if they think the tutorial lacks some particular chapter, etc. If you have suggestions, comments, or constructive criticism, please sent it to me by e-mail: borja AT borjanet DOT com. However, before contacting me with your impressions, please take a look at the "To Do" list to see what is already planned for future versions of the tutorial.
Then the best place to visit would be my weblog, BorjaNet :-)