How to attach attachements to incident

--- Write BR on 

Table : Sys_Attachment.

updateRecordForAttachment();

function updateRecordForAttachment(){

 var gr = new GlideRecord(current.table_name);

if(gr.get(current.table_sys_id)){

  gr.work_notes = "Attachment: " +current.file_name + " has been attached.";

  gr.update();

}

}