How would i go about adding to the body of a HttpWebRequest?

The body needs to be made up of the following 

<?xml version="1.0" encoding="utf-8"?>
<ChangeConfiguration xmlns="http://schemas.microsoft.com/windowsazure">
   <Configuration>base-64-encoded-configuration-file</Configuration>
   <TreatWarningsAsError>true|false</TreatWarningsAsError>
   <Mode>Auto|Manual</Mode>
</ChangeConfiguration>

Any help is much appreciated

c# azure configuration-files
Edit
Report