I want to try some skill that can help me to better my career in project management especially for someone who doesn't have the formal qualifications for it but with 7years experience
It's fantastic that you have 7 years of work experience to build on. That is a massive asset because project management is fundamentally about real-world coordination, not just pieces of paper.
To make sure we tailor this transition perfectly to your background, could you tell me a bit more about what you've been doing during your 7 years? For example, have you led teams, managed budgets, or coordinated any projects, even if "project manager" wasn't your official title?