'I' and 'me' are allowed in formal writing. However, your instructor is looking for a piece of descriptive writing in which there is no narrator present.
If, for example, you choose to write about a beach that you love to visit, you will simply use sensory (sight, sound, smell, tactile) language to describe it rather than telling about 'My Day at the Beach.'
So, instead of saying, 'I felt a gentle breeze,' or, 'We loved to watch the shadows of the beach grasses lengthening as the sun came up over the cliff,' you will say something like: At daybreak, a gentle breeze began to stir the leaves. The sun, appearing over the cliff, caused the beach grass to cast slender shadows.'
I hope this is helpful,
PS: Without any context, I cannot help you with the words 'Display Department.'