Hypothesis Testing with proportions

Calculate and interpret the Z-scores to test significant difference between the proportion of rates of dementia between
a. 30-49 year-old US men and 30-49 year-old NFL retirees (n=374).
b. 50+ year-old US men and 50+ year-old NFL retirees (n=670).

ll US Men
30-49: 0.1%
50+: 1.2%

NFL retirees
30-49: 1.9%
50+: 6.1%

I have the formula meant for this problem. I am confused as to which numbers I plug in for N1 and N2 since they are testing within the same group, do I use the same n (374)? and since they are percents, do I need to convert them to proportions?