layerZeroBridge/contracts/sender.sol

// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.0;

import "@layerzerolabs/solidity-examples/contracts/lzApp/interfaces/ILayerZeroEndpoint.sol";

contract sender {
  ILayerZeroEndpoint public endpoint;

  constructor(address _endpoint) {
    endpoint = ILayerZeroEndpoint(_endpoint);
  }
// an endpoint is the contract which has the send() function
  function send(address _remoteAddress, uint16 _dstChainId) external payable {
// remote address concated with local address packed into 40 bytes
    address localAddress = address(this);
    bytes memory remoteAndLocalAddresses = abi.encodePacked(_remoteAddress, localAddress);
// call send() to send a message/payload to another chain
    endpoint.send{value: msg.value}(
      _dstChainId,                   // destination LayerZero chainId
      remoteAndLocalAddresses, // send to this address on the destination
      bytes("hello"),          // bytes payload
      payable(msg.sender),              // refund address
      address(0x0),            // future parameter
      bytes("")                // adapterParams (see "Advanced Features")
    );
  }

}