How to begin with Fst calculation of SNPs from two different populations

Question

[doodle]

Hello,

I have two different populations and have identified a set of variants whose frequencies differ in the two populations. I now need to calculate Fst for those SNPs to identify genomic selection. I'm not able to figure how to start with the work. I have imputed data for the SNPs in gen.gz format and also excel data for those SNPs and their allele frequencies.

Any help to begin with the work please?

Thank you!