SFTP specifications

Hi, I have problem about Permalink , I just inastll my wordpress and I'm very beginer for SEO thing can you tell me about how to set up this like domain.com/page/post.html or it can not ?and why my New Release Product Blog can not show .htmland how can I change them ?So why my host no need to change .htaccess ?What its importance for SEOSorry I'm very stupid in this thing but trying to learn.