Learning this and I still don't get it. Can someone explain gaining the critical value, margin of error, and confidence interval, please?

Here are summary statistics for randomly selected weights of newborn girls: n = 36, x = 3180.6 9, s = 700.5 g. Use a confidence level of 90% to complete parts (a) through (d) below. a. Identify the critical value to /2 used for finding the margin of error. ta/2= (Round to two decimal places as needed.)