Delete and Edit the xml file nodes

Question

This is my input sample.xml


<users>    
    <user name='aaa' password='111' status='0' expireson='2012-12-31' createdon='2011-05-31'>
    <user name='bbb' password='222' status='0' expireson='2012-12-31' createdon='2011-05-31'/>
    <user name='ccc' password='333' status='0' expireson='2011-12-31' createdon='2011-05-31'/>
    <user name='ddd' password='444' status='0' expireson='2011-12-31' createdon='2011-05-31'/>
</user>




I need to delele the user tag (name as 'aaa') also
I need to edit the expireson on the user tag(name as 'ddd')


I'm new to c# language. I dono how to do this.




My sample Code for delete:


XmlDocument doc = new XmlDocument();
doc.Load(sample.xml");                    
XmlElement elmRoot = doc.DocumentElement;
string xPath = "/users/user[@name='aaa']";
XmlNode findnode = elmRoot.SelectSingleNode(xPath);
elmRoot.RemoveAll();  
doc.Save(sample.xml");


But not working.




For editing  i don't have any idea.


Please any help me.