Finding $p$ value corresponding to $z$ value, using the table with standard normal probabilities
Assuming a table for both negative and positive $z$ values, showing lower tail probabilities
Two sided 
$p$ value is the probability of finding the observed $z$ value or a more extreme value, given that the null hypothesis is true.
If you have found a positive $z$ value ($z \geq 0$):
If you have found a negative $z$ value ($z < 0$):

Right sided 
$p$ value is the probability of finding the observed $z$ value or a larger value, given that the null hypothesis is true.

Left sided 
$p$ value is the probability of finding the observed $z$ value or a smaller value, given that the null hypothesis is true.
