Hello Pitri,
you started directly on a higher level of construction 😉
What exactly is your problem?
First you need to know: If you want to install a drawer system in your cabinet, you need a drawer front!
Then you have to look: between the 2 parts of the drawer system there is a “volume” (it is surrounded by thin, light blue lines). When you construct your wooden drawer, you need to place your parts in this volume.
Try to open a project that is in the gallery. Maybe you can learn from this project.
If you have any questions, don’t hesitate to ask again.
Best regard
Woody