Welcome To WmUsers!!
what VAN you have to use…your company/client can answer you this…
Actually there are lot of EDI VAN providers like GXS,SterlingCommerce,IBM,CLEO,Inovis etc…
webMethods IS/EDI Adapter is the tool for translation documents to EDI formats.
Basically you need to install EDI Adapter comes with IS unless your company bought license for getting EDI module.
Please go thru the EDI Adapter documentation that comes with EDI Adapter after installation on IS ,referece this location WmEDI/docs folder you will see the Userguide.pdf’s or visit Advantage.webmethos.com for EDI tutorials.
Regarding basic understanding of EDI world visit ediuniversity.com
Note:Search this forum for webMethods EDI related questions you will see numerous posts and replies.