That is what training is for!!!
Do not expect to learn ANY 3D parametric CAD program by sitting down in front of it and just start creating models. Even creating a simple cube requires knowledge of the commands and processes.
There are some tutorials that may help you get started, but don't expect them to cover the full functionality of the software. Even with 15 years on Wildire/Creo and another 15 years before that on UG/NX, I still find new ways to do things.
