Essays / An Animal Encounter. that is my topic for my essay that the Professor assigned. [4]

I must write a Descriptive essay on an encounter i have had with an animal. but what i do not understand is that i must have a work cited page. How do i site a paper that is based on something i have encountered and nobody else has if this information is coming only from me? please help. i tried asking my professor on what he meant but he said he was going to put an example on his page. which he did not at all. please someone help me understand what he means thank you in advance