What is this type of query called, and how can I formulate it?

Question

I have following tables:

events(event_id, name, description)

groups(group_id, event_id, title, description)

event_group(event_id, group_id)

users(user_id, name, email)

event_user(event_id, user_id)

group_user(group_id, user_id)

As an example, how can I return the users who belong to a certain group which belongs to a certain event?