Add xml text after duplicate child node in existing xml file in c#

I have following xml file:

<?xml version="1.0" encoding="UTF-8"?>
<Report xmlns="http://schemas.microsoft.com/sqlserver/reporting/2005/01/reportdefinition" xmlns:rd="http://schemas.microsoft.com/SQLServer/reporting/reportdesigner">
    <DataSets>
    <DataSet Name="Data">
    <Query>
    <DataSourceName>DS1</DataSourceName>
    <CommandText>text</CommandText>
    </Query>
    </DataSet>
    <DataSet Name="table22">
    <Query>
    <DataSourceName>DS1</DataSourceName>
    <CommandText>New text2</CommandText>
    </Query>

in above xml file i have to add followeing xml text after end of first "Query" element.

 <Field Name="CommunicationDataValueId">
    <DataField>CommunicationDataValueId</DataField>
    <TypeName>System.Int64</TypeName>
    </Field>
    <Field Name="DeviceMasterId">
    <DataField>DeviceMasterId</DataField>
    <TypeName>System.Int32</TypeName>
    </Field>

and then i have one more xml text to add after end of second xml "Query"

<Field Name="Min">
          <DataField>Min</DataField>
          <rd:TypeName>System.String</rd:TypeName>
        </Field>
        <Field Name="Max">
          <DataField>Max</DataField>
          <rd:TypeName>System.Int64</rd:TypeName>
        </Field>

i am new to xml,please any help appreciated