Using the F1 in Jetech Keyboard
It seems like the top row of keys on your mac are configured to behave as function keys only in combination with fn key (bottom left). Follow the steps below to change the setting


Choose System Preferences from the Apple menu.
From the View menu, choose Keyboard.
Click the Keyboard tab.
Enable "Use all F1, F2, etc. keys as standard function keys".
Close System Preferences.


Now the blue color functions in top row will act in combination with fn key and esc, f1, f2 etc will behave as standard function keys.