Understanding how Models and Forms affect one another and database - django

Question

I am creating form for users to input information too. I then want to save that information to a database and be able to extract information.
I am having difficulty however when I try to create a drop down list and multiple selection list. For example say I define a model as in my models.py file as such:
gi_category = models.CharField(max_length=4, choices=GI_NOGI)
Where I have GI_NOGI specified as
GI_NOGI = (('GI','GI'),('NOGI','NO-GI'))
My forms.py looks something like this
class RegisterForm(forms.ModelForm):
weightclass = forms.ChoiceField(choices=WEIGHTCLASS, required=True,label='Weight Class')
gi_category = forms.MultipleChoiceField(choices=GI_NOGI, label='Contest You Intend to Enter', widget=forms.CheckboxSelectMultiple(), required=True)
class Meta:
model = Register
fields = ['name', 'age', 'birthdate', 'address', 'city', 'state', 'zip',
'phone', 'email']
labels = {'name':'Name', 'age':'Age on April 21', 'birthdate':'Birth date',
'address':'Address', 'city':'City', 'state':'State', 'zip':'Zip',
'phone':'Phone', 'email':'Email'}
widgets = {
'birthdate':forms.TextInput(attrs={'placeholder': 'MM/DD/YYYY'}),
'phone':forms.TextInput(attrs={'placeholder': '(###)-###-####'})}
Now I believe I am overwriting the gi_category and weightclass from models somehow because I cant access their respective values in the database. I don't know how to create a SelectMultiple any other way than I had I did(If this is problem any insight would be great.
I am wondering what I am doing wrong?
Also on a related note I want to have a database value for gi_category in which it can either have values of 'NO-GI' or/and 'GI'
I am saving the form values using this views.py
WEIGHTCLASS = (
('MFYW','Men Fly Weight(129 lbs. & Under)'),
('MBW','Men Bantan Weight(130 lbs. to 139.9 lbs)'),
('MFEW','Men Feather Weight(140 lbs. to 149.9 lbs.)')
)
GI_NOGI = (('GI','GI'),
('NOGI','NO-GI')
)
class Register(models.Model):
"""register some text"""
name = models.CharField(max_length=200)
age = models.CharField(max_length=3)
email = models.EmailField(max_length=200)
birthdate = models.DateField()
address = models.CharField(max_length=200)
city = models.CharField(max_length=200)
state = models.CharField(max_length=200)
zip = models.CharField(max_length=5)
phone = models.CharField(max_length=14)
weightclass = models.CharField(max_length=4, choices=WEIGHTCLASS)
gi_category = models.CharField(max_length=4, choices=GI_NOGI)
def __str__(self):
"""Return a string represenation of the model."""
return self.weightclass
Thanks