This is pretty easy. Just reply to this email and put your notes about each check-in *below* that venue's name.
Leaving some blank is fine.
You can visit http://lastnightscheckins.com/notes to see (and edit) your notes later on.
++ Dec 29, 08:38 PM @ Outlook Amusements (43916199) ++
++ Dec 29, 04:04 PM @ The Bangkok Restaurant (43816093) ++
-*-*- end email -*-*-