I have used Fiddler...
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/IETechCol/dnwebgen/IE_IntroFiddler.asp

to discover the soap request I need to post and I want to use the HttpWebRequest to make the post.

It has headers that are not properties of the httpwebrequest class.

Accept: */*
Referer: http://wpdwwa00/crn/pat/rsapp.htm
soapaction: http://developer.cognos.com/schemas/bibus/2#reportService
Content-Type: text/xml; charset=utf-8
Accept-Encoding: gzip, deflate
User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; SALT 1.0.5507.1 0111 Developer; .NET CLR 1.0.3705; .NET CLR 1.1.4322; .NET CLR 2.0.40607)
Host: wpdwwa00
Cookie: cc_session=home:w|tabs:|view:l|s_cc:|s_conf:na|s_sch:td|s_serv:na|s_disp:na|s_set:|s_dep:na|s_dir:na|s_sms:dd|s_ct:sa|lines:15|cols:3|ls:|refresh:30|e_hp:CAMID(*22WPCDWA01*3au*3aauthid*3d431146513*22)|e_proot:Public*20Folders|e_mroot:My*20Folders|e_user:Geoff*20Switz|ucap:armqm|ui:|e_root:|write:true; cam_passport=101:08b50b8e-937a-23e9-20e7-22cb2a357680:0112182037; CRN=contentLocale%3Den-us%26productLocale%3Den%26format%3D%26timeZoneID%3DAmerica%252FNew_York%26; AS_TICKET=1124796644sPvb6QGF
Proxy-Connection: Keep-Alive
Pragma: no-cache
Authorization: Negotiate TlRMTVNTUAADAAAAGAAYAHgAjgAAABAAEABIAAAADgAOAFgAAAAQABAAZgAAAAAAAACmAAAABYKIogUBKAoAAAAPUgBJAEMASABNAE8ATgBEAE4AUgBHAE8ANAAyADMATwBWAE4AOQA2ADAANAAzALxVBvvRGtvjAAAAAAAAAAAAAAAAAAAAAOj32Vne3cdlTqVam5j2jD46EjGO0qA8qD==
Accept-Language: en-us
Content-Length: 18711

How can I add these headers to my request?

Thanks,

Geoff