Help, I need backlinks.

I need some guidance on backlinks for an SEO newbie. I manage 2 x websites for marketing and they both need more backlinks. One site doesn’t even have a blog component so I will build one and start adding blog content. The other site has over 50 old/stale blog posts. But besides actually writing and posting the blog content, how exactly do I get backlinks and encourage linking? Any success stories or advice would be super appreciated. 😃