What is the success rate percentage of businesses with SEO?

[Serpa]

Very smart people have gathered here, you use such words that I did not understand a lot. I would like to consult with you. I have my own site, I built it myself, on a free constructor, but it hangs idle for me. I wanted to launch it through advertising, looked at the prices for their services, and changed my mind. You write for backlinks, what kind of links they are, how they work and what their prices are, I would like to know in more detail where to find such a server...