Ah, have you not installed Package Manager yet? That helps a lot. Granted, you have to copy the code for Package manager into the apps code in the same way. You first have to go into settings and enable developer tools for those to appear on the GUI. After enabling dev tools, you will have a new section on the left menu that you can expand to show Apps code and Drivers code.
So you have to copy the code into those spots for an app or driver. Just click on "new app" in apps code or "new driver" in driver code, and paste the code in and save. Then once the code is there, you go to Apps and "add app" and it will be a user app, not a built-in. You will be brought to the installation page when you select it. For drivers it will appear in the list of drivers on the device info page of a device.
Package manager avoids all that, but you have to do it the manual way once to install Package Manager. Then the package manager app will let you search for community apps and drivers, which you can then just select for install without having to do any code pasting.