To connect your gateway to The Things Stack Community Edition, it has to be configured to properly forward the traffic to it, and it also has to be added/registered on The Things Stack Community Edition.
It is recommended to use LoRa Basics Station protocol, due to a number of security and scalability issues related to the UDP Packet Forwarder.
To add a gateway, you will need to provide Gateway EUI and its Frequency Plan. Some other optional parameters can also be defined.
Registering your gateway can be done in two ways, via Console or via CLI.
More detailed instructions for adding gateways are available in the official The Things Stack documentation.
If you are experiencing issues while adding gateways to The Things Stack Community Edition, see Troubleshooting.