GWAS to gene function prediction

Question

[alnus]

I have GWAS result and there using LD decay information, I search in the gff file then found some gene in my region. Unfortunately, no information of gene attached in the gff file. I would like to retrieve their sequence and try to blast it in the publicly available database. I find difficulties to find some good tutorial to do so, I wonder is there any helpful tutorial that suits a beginner in informatics? I have familiarity in R but pretty new in Python.