。
She wore a new dress for the party.
Literal
She [topic-は] party [genitive-の] [for the sake of-ために] new dress [object-を] wore.
着る ('wear, put on') is specifically for clothing worn on the upper body or torso — shirts, dresses, coats. Trousers, skirts, shoes, and socks take 履く (はく) instead, while hats use かぶる, gloves use はめる, and accessories use する. This finely articulated wear-verb system is one of those quietly intricate corners of Japanese vocabulary; the choice of verb signals what part of the body is involved before the noun is even out.