Here are the steps to make an Apple Keyboard discoverable:

1. Turn on your keyboard by pressing the On/Off button on the side of the keyboard, along the top right side.
2. Click the Apple icon from the top left of your Mac computer screen and then select "System Preferences."
3. Click "Set Up Bluetooth Keyboard."
4. Select your keyboard from the list of Bluetooth devices that appear.

That's it! You should now be able to use your Apple Keyboard with your device. If you have any other questions or need further assistance, please let me know.

I hope this helps! 😊