From an old post: To start out with XML-Schema this might be of interest to you:

XSD-Tutorial: http://www.liquid-technologies.com/XsdTutorial_01.aspx

Free graphical Tool: http://www.liquid-technologies.com/LiquidXMLStudio.aspx

[2009-06-27] Update: A very cool feature is the generation of a Schema, based on example-XML files you give Liquid XML Studio! I discovered this when I built a Schema that would not validate against my desired XML structure and I could not figure out why. I generated the XSD like this:

• Open one of your XML examples with Liquid XML Studio.
• Select from the menu “Tools / Infer XSD Schema”.
• You are asked for more examples. I did it with just one XML file.
• And bingo: You have your XSD.

As I did a diff of my handcraftet version of the XSD and the generated one, it revealed the reason for not validating nicely for me ;).

Cool tool, you can use with the 30-day trial licence.