What is a negated sentence?
When the action is cancelled. Other than that, you can also use negation to specify details about the cancellation.
I am sure.
> I am not sure. (general negation)
> I am never sure. (detailed negation)
Ek is seker.
> Ek is nie seker nie.
> Ek is nooit seker nie.
You could use the first NIE after the first verb and the second NIE at the end of the sentence. Another way to look at it -- the subject is first, the verbs is second, and the negation goes in the third place.
Use Negation terms to specify the type of negation, e.g. (never, nothing, nowhere, etc.). These terms would replace the first NIE.
Examples (languages mixed):
I feel wonderful. > I feel NIE wonderful NIE.
We did help. > We did NIE help NIE.
We will help. > We sal NIE help NIE.
We can help. > We can NIE help NIE.
We never helped. > We did NOOIT GEhelp NIE.
We will NOT help AT ALL. > We sal GLAD NIE help NIE.
We can help with nothing. > We kan met NIKS help NIE.