You can do the analysis in Plink https://www.cog-genomics.org/plink/2.0/. I guess it is the easiest way, there are other software that also can perform GWAS
Hi, The first step is quality control (QC) in plink. Then there are two popular method for GWAS: Fixed linear regression model in plink, and linear mixed model in softwares such as GCTA , GEMMA and ....