Con not connect an monitor to USB-C

Good day,

I was used to work with an Macbook Air (with USB-3) and an Apple monitor. Both was connected with a Thuderbold cable.

I received a new MacBook air with USB-C port. I also recieved an Thunderbolt 3 to Thinderbolt2 adaptator

The devises can be connected but when I turn on my new Mac, the screen does not work.

I have no idea, why it does not work and it should. Should I change some configuration?

Are the devises compatible with Thunderbolt 2 and 3 and USB-C?

Thank for your advise?

Cheers