I need to write a letter to improve my credit repo

I need to write a letter to improve my credit report. I need to get the debt collector and the original creditor to make changes to mark my record as “Paid in Full.” I guess I need to have the collector to remove the negatives and the original credit to mark as “Paid in Full.” However, I do not know if I write just one letter making my request to the collector or write to both the collector and creditor separately.
I have been looking at the sample letters at debtconsolidationcare.com I do not see a letter that covers both. Can someone help me on choosing the correct letters?