There's a Normal Table(I think Appendix 5 in your book) where you look up the Z figure on the left column side.
If P(Z < a positive number), then whatever number matches with the number on the left column is p.
If P(Z < a negative number), then 1 - P(Z < positive number of this instead)
P(Z > a negative number) = P(Z < a positive number)
P(Z > a positive number) = 1 - P(Z < this same positive number)