Hello I have a bit of a problem how to use the normal approximation interval(

Binomial proportion confidence interval - Wikipedia, the free encyclopedia ). I would be very happy if anyone could explain further!

I am trying to calculate the upper probability of an error, say I have a confidence level of 25%. There are 6 people voting for YES and 0 people voting for NO. The result should be 0.206 or the predicted number of errors would be 6 * 0.206 = 1.236.

Could anyone spare the time to explain how this is calculated? I am completely stuck, thank you very much!