How do I get a free and quality backlink?

Yes. You can get backlink from each website but getting a backlink from a random website on the internet would not be helpful. Your backlinks should be from authoritative and reputable websites. Moreover, the website that you get backlinks should have a similar content to your website. Otherwise, it should not seem organic backlink to Google. In short, if you did not pay for your backlinks, if they are from authoritative and reputable websites, if websites have a content which is similar to your website, you can be sure that your backlinks are of good quality.