If you want a straightforward, legal copy of 'Jane Eyre' right away, I usually go straight to Project Gutenberg. Their site hosts public-domain classics and 'Jane Eyre' is there for free in multiple formats. The direct page is https://www.gutenberg.org/ebooks/1260 where you can read in your browser or download EPUB (with or without images), Kindle format, plain text, or a zipped folder. I tend to grab the EPUB for my phone and the Kindle file for my e-reader.
Downloading is simple: open the book page, choose the format you want, and the file will start. If you prefer to just skim, the HTML version opens instantly in your browser. For offline listening, LibriVox offers free public-domain audiobooks of 'Jane Eyre' read by volunteers, which I sometimes play while doing chores. Keep in mind that some editions labeled 'Jane Eyre' might include modern introductions or notes that are copyrighted; Project Gutenberg generally provides the original text.
If you like nicer typography, check out 'Standard Ebooks' or 'ManyBooks' — they reformat public-domain works into cleaner, modern EPUBs. For archival or research uses, the Internet Archive has scanned editions with original typesetting. Personally, I love switching formats depending on mood: EPUB for cozy night reading, text for quick searches, and audiobook for long drives.