Complex sentence: On January 8, Karen, Hikaru, Risa, Rina and Waka participates in Stardust Section 3 (Event) Ore no Next Girl 2017 ～ Mochiron Fujii ～ they won the first place and the opportunity of acting in Stella Ball.
Split into simpler sentences: On January 8, Karen, Hikaru, Risa, Rina, and Waka participated in Stardust Section 3 event Ore No Next Girl 2017 Mochiron Fujii. They won first place and the opportunity of acting in Stella Ball.