To quickly review: the characteristics of Monopolistic Competition tell us the following:

Many Firms: No single firm is sufficiently large enough to affect the demand curves faced by other firms.
Product Differentiation: Each firm sells a product that differs in some way from that of all of its competitors, so each firm faces a downward sloping demand curve.
Free Entry: Long run profits are zero. Firms enter the industry when it is profitable until profits return to zero, losses lead to exit until profits return to zero.