Do This As Per The Link
class SignUpForm(UserCreationForm):
# My Own Custom Fields
username = forms.CharField(forms.TextInput(attrs={'class': 'form-control', 'placeholder': 'Username'}))
first_name = forms.CharField(forms.TextInput(attrs={'class': 'form-control', 'placeholder': 'First Name'}), max_length=32, help_text='First name')
last_name=forms.CharField(forms.TextInput(attrs={'class': 'form-control', 'placeholder': 'Last Name'}), max_length=32, help_text='Last name')
email=forms.EmailField(forms.EmailInput(attrs={'class': 'form-control', 'placeholder': 'Email'}), max_length=64, help_text='Enter a valid email address')
password1=forms.CharField(forms.PasswordInput(attrs={'class': 'form-control', 'placeholder': 'Password'}))
password2=forms.CharField(forms.PasswordInput(attrs={'class': 'form-control', 'placeholder': 'Password Again'}))
# The Default Fields Of The UserCreation Form
class Meta(UserCreationForm.Meta):
model = User
# I've tried both of these 'fields' declaration, result is the same
# fields = ('username', 'first_name', 'last_name', 'email', 'password1', 'password2', )
fields = UserCreationForm.Meta.fields + ('first_name', 'last_name', 'email',)