This paper is the first of a series giving a self-contained way from the
Neveu-Schwarz algebra to a new series of irreducible subfactors. Here we
present an elementary, progressive and self-contained approch to vertex
operator superalgebra. We then build such a structure from the loop algebra
Lg of any simple finite dimensional Lie algebra g. The Neveu-Schwarz
algebra Vir1/2 emerges naturally on. As application, we obtain a unitary
action of Vir1/2 on the unitary discrete series of Lg.Comment: 40 page