You can host another streamer's twitch channel on your own channel by following these simple steps.
• Go to https://www.twitch.tv with your web browser, and then sign in or sign up. The button is located at the top right corner of the twitch interface.
• Still at the top-right corner of your interface, after signing in, click on your username. There will be a drop-down option.
• From the options, click the channel. Your chatroom would be located towards the right of your channel.
• In your chatroom, type "/host (channel name in your chat)." For example, if you're hosting the main channel, type "/host twitch." This will make your channel viewers be able to view the channel you are also hosting.
However, if you are using your app on your phone, follow these steps after you must have logged in.
• Click on your profile picture, and locate the chat button under it.
• Press the chat button to display your channel's chat. In the chat, type "/host (the channel name)."
In case you want to stop hosting, just type "/unhost".