How to Set Multi-Select choices in admin django

I have a model

class Event(models.Model):

    event_name = models.CharField(max_length=100, default="")
    event_organizer = models.ForeignKey(Organizer, on_delete=models.CASCADE)
    event_type = models.ForeignKey(Type, on_delete=models.CASCADE)
    event_city = models.ForeignKey(Citie, on_delete=models.CASCADE)
    event_tag = models.ForeignKey(Tag, on_delete=models.CASCADE)

I have a field event_tag. During add event form in admin panel i want to select multiple tags. how to do that and how to save them