BROWSER CACHING ERROR

Hi, I would really appreciate your help in fixing this error. I'm not a technical person for web development and this is why I have downloaded hummingbird because it seems it can help me with just a click of a button. I have downloaded your plugin as a trial atm so I hope it will be worth $50 a month for me to keep it running.

Anyhow the error I am getting is as follows:

Browser Caching is not working properly:- Your server may not have the "expires" module enabled (mod_expires for Apache, ngx_http_headers_module for NGINX)
- Another plugin may be interfering with the configuration
If re-checking and restarting does not resolve, please check with your host or open a support ticket with us.

Please, can you advise or help as best as you can.

Kind regards,
Terence