To write (a letter), draw up (a document), or compose/put down in writing; to write carefully or prepare a document.
夜になってから手紙をしたためた。
I wrote a letter late at night.
契約書をしたためてから双方が署名した。
They drew up the contract and then both signed it.
日記を毎晩したためる習慣がある。
I have a habit of writing in my diary every night.
To take a meal or to eat (often used for having a light meal).
仕事の合間に軽く昼食をしたためた。
I had a light lunch between work.
寒かったので温かいスープをしたためて体を温めた。
Because it was cold, I had some hot soup to warm up.