I'm not sure if this link will help you. I haven't used this before, but I believe it is for showing common SNPs in genomic data. You could probably use this to look up the common SNPs for the gene you want to study. But I think your goal is to show how to identify them in your own data. If so you should just align the sequencing data. Look up on youtube how to identify SNPs using an alignment. There should be a lot of different tools that show how to do this and visualize it.