To progress through an event, players must complete each Week of the main event questline. Weeks refer to the quests that are usually released after 3PM PST on each Wednesday of an event. By completing each Week you'll be able to unlock more content, such as characters and decorations. 

For example, here is how you play though an event: 
- Week 1: Begin "[Week 1 Quest] Pt. 1" and play until you complete "[Week 1 Quest] Pt. 8" 
- Week 2: Begin "[Week 2 Quest] Pt. 1" and play until you complete "[Week 2 Quest] Pt. 8"
- Week 3: Begin "[Week 3 Quest] Pt. 1" and play until you complete "[Week 3 Quest] Pt. 8" 

If you ever need to find the main event quest, it will usually be the first one listed on the quest log found on the left side of the screen.