How to access the nodes and its elements in XML using c#

Question

For example , I have an XML file like this 

 

<UAObject NodeId="ns=2;i=1001" BrowseName="2:PackMLObjects">

<DisplayName>PackMLObjects</DisplayName>

<References>

<Reference ReferenceType="HasTypeDefinition">i=61</Reference>

<Reference ReferenceType="Organizes" IsForward="false">i=85</Reference>

</References>

</UAObject>

<UAObject NodeId="ns=2;i=1002" BrowseName="2:PackMLMachine">

<DisplayName>PackMLMachine</DisplayName>

<References>

<Reference ReferenceType="HasTypeDefinition">ns=1;i=1008</Reference>

<Reference ReferenceType="Organizes" IsForward="false">ns=2;i=1001</Reference>

</References>

</UAObject>

<UAObject NodeId="ns=2;i=1003" BrowseName="1:Admin">

<DisplayName>Admin</DisplayName>

<References>

<Reference ReferenceType="HasComponent" IsForward="false">ns=2;i=1002</Reference>

<Reference ReferenceType="HasTypeDefinition">ns=1;i=1007</Reference>

</References>

</UAObject>

<UAVariable DataType="PackMLDescriptorDataType" ValueRank="1" NodeId="ns=2;i=1004" ArrayDimensions="1" BrowseName="1:Parameters">

<DisplayName>Parameters</DisplayName>

<References>

<Reference ReferenceType="HasComponent" IsForward="false">ns=2;i=1003</Reference>

<Reference ReferenceType="HasTypeDefinition">i=63</Reference>

</References>

<Extensions>

<Extension>

<si:VariableMapping>"PackTags"."Admin"."Parameter"</si:VariableMapping>

</Extension>

</Extensions>

</UAVariable>

 

 using c# i need to access all namespaces  <si:variablemappig> and its respectice values 

could anyone pls help me with code ?  i'm using VS studio 2015