How to insert the new element on XMLNode in C#

Question

I am trying to insert a new element into the XmlNode in C# code,

 

How to insert the <delimiter>@#<delimiter> element inside the "/TestBooks/template/field" root. 

 

 

Inside the <field> element, I need to insert the <delimiter> element, based on id element <Id>11-09-2020-505</Id>.