XML Schemas for X12 documents

Hi,

I am new to XML Schemas. I want to represent the X12 810 standard as an 
XML Schema and validate and x12-810 document(converted into xml) against 
this schema.

Can any one please let me know how to go about. Also if you could 
provide me with links that would help me in understanding the finer 
details, I would appreciate that.

Thanks
Vaidya