Hey @vietnamlawyer , I'm not sure your site is a Shopify one but I'll help nonetheless!
SEO is its own whole beast and takes a while to learn. It'd be way too difficult to tell you "what you need to do" in just one forum answer. You need to learn how to optimize your pages: for speed (your website is fairly slow), for SEO on-page (make sure you have a meta title/description, descriptive h1 tags and content on most pages). You need to create helpful content that makes Google want to rank your site higher... and get backlinks from other sites in your industry—if they see you as a leader, so will Google.
MoZ's Beginner Guide to SEO is a great place to start.
Let me know if that helped!