Drop-down list in Django

I am writing a simple online store on django 1.9. The following models are available:

tovar/models.py

class Color(models.Model):
    color = models.CharField(verbose_name="color", max_length=25, blank=False, null=True)
    code = models.CharField(verbose_name="color code", max_length=8, blank=True, null=True)

class Tovar(models.Model):
    Color = models.ManyToManyField(Color, blank=