insert into existing xml using c#

Question

hi

i am new to c# and xml. i have a xml file named names.xml  like this

<names>

              <students>

                                 <student>A</student>

                                <student>B</student>

             </students>

            <teachers>

                                 <teacher>X</teacher >

                                < teacher >Y</teacher >

             </teachers>

</names>

now i want to insert D into student tag. when i insert it will insert outside of students.

how can i insert D into students using c#. any idea or help  please...