。
She informed her parents of her success.
Literal
She [topic-は] her own success [object-を] parents [to-に] informed.
知らせる ('to inform, let know') is the causative-style verb derived from 知る ('to know') — etymologically 'to make X know.' Takes an indirect object (the person informed) with に and a direct object (the content) with を — a clean ditransitive frame. 両親 ('both parents, parents') is the formal/neutral word for one's parents; 親 alone covers parents more broadly, including stepparents.