problem+with+richtextbox

hey i have created a mailmerge sort of application in vb. i have prepared a .rtf file which contains a letter format in a formatted way. i am loading that file in the richtextbox. now i want to search for tag names like &cname& and replace with value from the database. this i want to do for all the records in the database. after this i want to copy the text from richtextbox to some other file so this file should contain letters for all clients and the formatting of template file should also be preserved. can someone please tell me how do i achieve this.
thanx in advance.