Under your name at the end of the letter, skip two lines. On the third line, write "Enclosure:" or "Enclosures:" if there are multiple documents. Skip a line after "Enclosures:" and then begin your list of enclosures. Put each enclosed document title on its own line.
On a paper business letter, you often include the CC line underneath your signature, either above or below any enclosures line. Here are the various abbreviations you can use to note carbon copy on printed business letters: cc: c.c.
Formally, you would refer to the enclosed items in the body of your letter followed by (enclosed) and then, under the signature at the end of the letter you'd write "Enclosures (x)" where x is the number of enclosures.
In a printed letter, the CC line might go before or after the enclosures line. Whichever you choose, it needs to be below the signature line.