(A) Two-sided test is H0: p = p0 vs. H1: p not = p0
(B) Alpha = something
(C) Calculate probabilities in tails of binomial distribution assuming X~b(n, p0). These probabilities can be calculated with EpiTable | Probability | Binomial: Proportion vs. Std.
(D) Conclusion: Reject H0 if p < alpha.