I suggest this slightly outdated video series: https://www.youtube.com/watch?v=aV6kFxH3Xws
This is also a tutorial that covers a larger number of features: https://www.youtube.com/watch?v=pEETxSxYazg
Did you try the tutorial from the documentation (https://doc.qt.io/qtdesignstudio/qtdesignstudio-loginui1-example.html)?