Got thrown in project manager position with no prior experience. HELP

Background story. I am a freelance mobile app developer and got thrown in a mid-size(?) software development project. The idea is there but Im tasked to form the team and start from scratch. I have never done something like before and every task at hand looks gigantic right now.

• where do I find potential teammates?
• how do I even plan this development as I have never worked in a team before?
• is it better to outsource the whole project to a development company and oversee the process?

I've looked into software development cycles so I get the gist of the flow(?). I guess what I want to know is… as a project manager, what are my duties when it comes to setting up the team and moving forward? It would be a great help if someone can guide me to a learning website that explains such as I could not find them at all.