If you have already created a bot, then copy your telegram token and skip to Step 2. If you have lost the token, then use the /token command and select you bot to retrieve it.
Otherwise use the /newbot command to create a new bot. The BotFather will ask you for a name and username, then an authorization token is generated for you.
The name of your bot is displayed in the contact details and elsewhere.
The Username is a short name, to be used in mentions and telegram.me links. Usernames are 5-32 characters long and are case insensitive, but may only include Latin characters, number and underscores. Your bot’s username must end in ‘bot’, e.g. ‘tetris_bot‘ or ‘TetrisBot‘.