You want your online contacts / audience to be informed of what happened to you, so you need to give access to your Inbox, facebook account, etc. to a trusted person. This is well explained by these question and relative answers on quora: "I want my wife to get access to my passwords of Google, Facebook etc. after I die, but not when I am alive".

You can write down all your credentials (email, facebook, personal computer, etc.) on a sheet of paper, hide it somewhere and prepere a notice to let your digital representative know where to find it.