How to connect MacBook Air 2017 to a monitor?

Hello,

I have a MacBook Air 2017 with Thunderbolt 2. I bought an external 4K LG monitor for it with 2xHDMI and 1xDisplayPort. I have used an DisplayPort to HDMI adapter as connection between my Mac and monitor, with no luck. Monitor works fine using HDMI cable that has been added as a part of purchase on Windows monitor. I’m guessing that the adapter I have used, seems to be not working properly. I don’t want to spend money on adapters that won’t work so I’m asking for help. Could you please advise me, what is the best option how to connect MacBook to external monitor as I am new in the Apple world.