You are Jane. Write a letter to Bessie describing your new job as governess and your new employer, Mr. Rochester.
This is an interesting assignment, and can be used not only to show knowledge of crucial chapters in Jane Eyre but also of the period as a whole.
First, you need to invent a fictional occasion for writing – perhaps an object Jane thinks she might have left behind while packing – because there is nothing in the text that would suggest such a letter likely, nor is there a suggestion that Jane had regular correspondence with Bessie.
Next, think about what sort of details would be included. Would Jane reveal the complex emotions the narrator tells us about in a letter to Bessie or would she simply recount the basic events and situation, e.g. that Adele, her pupil, is a young French girl, the size of the household, etc. For Rochester, the size of his fortune, his appearance, and a small amount of biographical information might be appropriate.
You might also want to look at letter-writing manuals of the period such as the Ladies Complete Letter Writer to get a sense of the appropriate generic conventions.