Replace <div> of page with <div> comes from $.ajax response

Question

Problem is written inside the success section.

$.ajax({
    url : 'path to file',
    dataType : 'json',
    type : 'POST',
    data: data,
    success : function(res)
    {
            // here I want to recive <div> in response.
            // then replacing the received <div> with existing one.
            // I don't know how I could send <div> in response.
            // How would I receive <div>, 
            // and How to replace it with the existing one.
             
    },
    error : function()
    {
            alert("failed");
    }
});