Where can I find Galois original paper?
A google search for his 1897 collected works, Oeuvres mathematiques d'Évariste Galois, turns up quite a few freely available copies:
copy at Internet Archivev
copy at Christophe Clanet's web pages
copy at google-books
copies at Project Gutenberg
Gallica's copy of some work published in 1846 in Liouville's Journal
Oeuvres mathématiques d'Évariste Galois by Évariste Galois is the PDF article in French about some of his published works.