1. Open conversation with @BotFather.
2. Post /start, and you will see:

1. Post /newbot
2. Post name and username
3. Done, after you get ​token​ like as 680788960:AAEKP9xGSZK9uyWGGouZFYmTkCN8i_y0w

Sending message to channel:

1. Open url or get => https://api.telegram.org/bottoken/sendMessage?chat_id=chat_id&text=test
2. Done

Finding chat_id:

1. Add bot to as ​channel administrator
2. Post /start to send bot command
3. Open url or get => https://api.telegram.org/bottoken/getupdates
4. See channel_post.chat.id
5. Done

for more api kindly goto https://core.telegram.org/bots/api