New to be a UX designer

I have a personal project about redesign an existed app..what is the first thing to start with? I had a survey from this company(2020 I guess not recent, and I do not have anyway to find email or real user to talk with) I love UX design is because I love talk to people and do want to understand what they needs and what’s the real problem behind what they saying but the problem I had now is..it is really hard to contact with the real users .. what should I do