To define how the supernatural is used by the author in Jane Eyre by Charlotte Brontë, it is important first to understand the meaning of "supenatural."
The Merriam-Webster Dictionary defines "supernatural" as:
...attributed to an invisible agent (as a ghost or spirit)
An example the site uses states:
...believes in ghosts, guardian angels, and other supernatural beings
The supernatural in a modern-day context makes one think most often of ghosts, demons or aliens. "Supernatural" refers to anything that is beyond the realm of what occurs naturally in this world. For instance, God is considered supernatural. The one place in Chapter Ten that refers to any element of the supernatural is seen in Jane's reference to "[a] kind fairy."
When Miss Temple, Jane's friend and mentor marries the Rev. Mr. Nasmyth and leaves Lowood, Jane realizes that her own contentment with Lowood rested firmly in Miss Temple's influence. Jane's "settled feeling" came from Miss Temple, as well as:
...something of her nature and much of her habits: more harmonious thoughts: what seemed better regulated feelings had become the inmates of my mind...
Once Jane realizes that she was only satisified with her life while in the company of Miss Temple, she is very much aware now that she cannot remain at Lowood, but must find a way to change her circumstances. There are not a great many options open to a woman of that era—most especially one raised at Lowood Institution. Jane quickly reconciles herself to the reality that she must go into service. ("Service" at that time meant being hired into a household to perform some kind of task: in this case, her training and education would make her a perfect candidate as a governess.) Jane is really already "in service" at Lowood, working as a teacher there. All she knows for certain is that she wants to go into service somewhere else. She is wise enough to know that this is her only option.
Jane begins to consider how she can gain employment elsewhere; but struggle as she may, no answers come to her. She has no friends to help her, and certainly no family connections that will come to her aid. She must make a plan and pursue it on her own. Still, she cannot imagine how to accomplish such a feat. Her thoughts chase each other around in her head:
There are many others who have no friends, who must look about for themselves and be their own helpers; and what is their resource?”
I could not tell: nothing answered me; I then ordered my brain to find a response, and quickly. It worked and worked faster: I felt the pulses throb in my head and temples, but for nearly an hour it worked in chaos, and no result came of its efforts.
At the height of her frustration, the "supernatural" comes to her aid.
A kind fairy, in my absence, had surely dropped the required suggestion on my pillow; for as I lay down it came quietly and naturally to my mind: “Those who want situations advertise; you must advertise in the—shire Herald.”
In Chapter Ten, Jane notes that when her mind cannot order her thoughts to devise a plan to leave Lowood, an "angel"—a heavenly being or messanger from God—gently brings the answer to her as if dropping it on her pillow.