How did you guys get started with facebook?

Hi, for a long time I was thinking of starting with fb ads. What I want to is to open a business and do fb ads as a service. To be more to specific I would do that for plumbers. The problem is that I only have general knowlage and have never done it before. So that leaves me with 3 options. First would be to get a job at an agency and hope they teach me something. Second would be to open a company offer my services for free while somebody from upwork would be teaching me. Third would be to pay for an ad spent to some business while being tought by somebody from upwork. I was also thinking to offer my services for free to first 5 people. What do you guys think, which option should I choose. Was somebody in a similar situation as I am currently in?