Managing the content of an XML file programmatically

I would like to manage the contents of a RSS Feed xml file programmatically.

The base file exists and contains:

<?xml version="1.0" encoding="utf-8" ?><rss version="2.0"><channel></channel></rss>

I now wish to add, update or delete <item> elements programmatically.

1) How to I get the base file in the first place?

2) How do I now add, update or delete <item> elements?

Your help would be much appreciated.  VB would be preferrred to C.

Thanking you in anticipation.

Roger