Summarize:

It's a white "F" on a blue background. If you aren't signed into Facebook, enter your email address (or phone number) and password and tap Log In. It's in the bottom right corner of the screen. It's at the bottom of the first list of options here. Doing so opens the Memories page. Facebook will display several different statuses, pictures, and other media from today's date for past years. You'll also see a section at the bottom of the page dedicated to days previous to today's date.
Open the Facebook app. Tap . Scroll down and tap See More. Tap On This Day. Scroll down through your memories.