Hi @DucLa. If you’re new to Katalon, I suggest you start with this beginner’s learning path. It will guide you on how to quickly automate UI tests with Katalon Studio. Then, after completing the path, you can join and get the Practitioner Certification.
After getting the certification, you will be confident in using Katalon to create reusable simple tests and run them regularly. Of course, it’s not the end point, you will need to continue to learn about other concepts, methodologies, and stuff to advance and be more efficient in test automation.