how can i play online

Sometimes it may not work if your DNS is not configured correctly. To change your DNS:

Windows:

Go to control panel, Network and Internet, Network and Sharing Centre, Change Adapter Settings, Click on your Wifi/Ethernet, Properties, then double click IPv4 or IPv6 (changing both is recommended) - then you can change the DNS to whichever server you want, I would recommend either 1.1.1.1 (Cloudfare DNS) or 8.8.8.8/8.8.4.4 (Google DNS)

This is for if Minecraft multiplayer is somehow blocked, etc

Hope this is somewhat useful!

-hz