How to parse XML for email notification?

Here is some example code in Set Authorisation Level Server Event that you can have a look at.

The following code will set the value of ManagerDisplayNextAuthSelection based on the value of PurchaseTotal.

Sub Main(ByVal K2 As ServerEventContext)
 K2.Synchronous = True

 Dim PurchaseTotal As double= CDbl(SourceCode.K2Utilities.XMLFieldMod.GetXMLValue(K2.ProcessInstance.XmlFields("K2InfoPathSchema").Value,"my:PurchaseOrder/my:Order/my:OrderPriceTotal"))

 If PurchaseTotal > CDbl(K2.StringTable("Level2ApprovalLimit")) Then 
  K2.ProcessInstance.XmlFields("K2InfoPathSchema").Value = SourceCode.K2Utilities.XMLFieldMod.SetXMLValue(K2.ProcessInstance.XmlFields("K2InfoPathSchema").Value,"my:PurchaseOrder/my:Manager/my:ManagerDisplayNextAuthSelection","True")    
 Else
  K2.ProcessInstance.XmlFields("K2InfoPathSchema").Value = SourceCode.K2Utilities.XMLFieldMod.SetXMLValue(K2.ProcessInstance.XmlFields("K2InfoPathSchema").Value,"my:PurchaseOrder/my:Manager/my:ManagerDisplayNextAuthSelection","False")  
 End If

End Sub

Example code in Timestamp Approval Server Event
The following code will set a timestamp into ManagerApprovalDateTime.

Sub Main(ByVal K2 As ServerEventContext)
 K2.Synchronous = True

 Dim sTimeStamp As String = Now.ToString("MM/dd/yyyy HH:mm:ss tt")
 K2.ActivityInstanceDestination.XmlFields("K2InfoPathSchema").Value = SourceCode.K2Utilities.XMLFieldMod.SetXMLValue(K2.ActivityInstanceDestination.XmlFields("K2InfoPathSchema").Value,"my:PurchaseOrder/my:Manager/my:ManagerApprovalDateTime",sTimeStamp)

End Sub

You can use the SourceCode.K2Utilities namespace to load an XML element and loop through the nodes in the element and add each node's value to your email - this code snippet should get you started:

.Value, "my:myXMLRoot/my:EmailElements"); 
      for (int i = 0; i < xmlNodeList.Count; i++) 
         {
          //do something with the value of the element, maybe append it to a string
          emailText += xmlNodeList.Item(i).InnerXml; 
         }