Please take the time to choose the correct forum for your posts. This forum is for questions on XML, not Ant scripts. For more information, please read this.
This post has been moved to a more appropriate forum.
Abder-Rahman, it would help is you were a little more specific about what software you are working with. I will assume you are asking a question about the Ant build.xml file. In that case I will forward you to the documentation: http://ant.apache.org/manual/CoreTypes/fileset.html
If after reading that you have some specific questions about it, then feel free to ask.