Marketing Strategy

I need advice on the initial marketing strategy, I have an Italian marketplace for freelancers like fiverr. I am also involved in digital marketing and social media marketing. I need to understand how to start advertising the site, attention the problem is that I do not know how to start because as there are not yet registered freelancers I cannot advertise to find employers and the same thing applies to advertising to find freelancers, as I do to have freelancers register if there are still no requests from employers, I hope to be able to make you understand my question, therefore I am looking for a person who will give me an initial consultation to tell me what to do.