Outbond iDoc for PO output

Hi Experts,

We are using ECC5.

My Client needs to send PO to vendor in XML format.

Can anyone give me steps to create Outbound iDoc to for PO ?

We will send the iDoc to XI and XI can convert it into XML format from there send to vendor.

We need both new and changed PO's to be send to vendor.

Any help appreciated.

Thanks