Welcome to TS.
I assume you want to find q1 and q3 for the standard normal distribution. For q3, since 75% of the scores are below this value and since the area under the curve is 1, the area below the score representing the 75th percentile is 0.75. To use the table, you would look for a score corresponding to 0.75. Looking at the body of the table, find the value closest to 0.75, and you can get the z-score from the column and row that corresponds to 0.75.
To find q1, keep in mind the normal curve is symmetric about zero...
Let me know if you need more help.