I find macOS to be much more pleasant than Windows.

> If you don't explicitly minimize the window and open another program, the other window is hidden. Where is it? How can I open it? Yes by minimizing every window until I have found mine.

I don't understand exactly what you mean.

> what happens if you have several windows open of that app?

One of these:

• Right-click/Control-click on the Dock icon

• Check the Windows menu of the app. Minimized windows will have a Diamond

• Press F3 to open Mission Control.

• Press Control+F3 to see all windows of the currently focused app.

• Press Alt+F3 to open Mission Control settings and configure them to your liking, along with setting Hot Corners for showing application windows etc.

• If you "Group windows by application" and have a mouse with a scroll wheel, you can use scroll the wheel when hovering over an app's window, to "spread" that windows stack.

• Press Option+Command+H to hide (not minimize) all windows except the active app.

While the UI UX in macOS has degraded a bit, minimizing windows you’re not using as the main way to manage a desktop is, I think, a Windows habit.

macOS works much better if you manage windows with hiding, rather than minimizing. Once you get the hang of it, with cmd-h (hide), cmd-tab (switch applications), and cmd-‘ (iterate windows of an application) I (almost) never leave the keyboard and can get right to the window I need quickly.