CustomGame.JoinChannel(Channel channel);
Syntax
public void JoinChannel(
    Channel channel
)

channel
Channel to join.
Type: CustomGameOW.Channel

Joins a chat channel.

The code below will send a message to everyone in spectators, then join match channel.

using System;
using CustomGameOW;

...

static void Main(string[] args)
{
    CustomGame cg = new CustomGame();

    cg.JoinChannel(Channel.Team); // join team channel (spectator)

    cg.Chat("Welcome to typical boss battle! You are currently in the queue, please wait.");

    cg.JoinChannel(Channel.Match); // join match channel
}