To customize your bot's profile, you will need to speak to the BotFather. Here is the link to chat with the BotFather https://t.me/botfather.
Type or select /mybots.
Next, you will be shown a list of your bots. Select the bot that you want to edit.
Select your bot and a menu of what you can do to the bot will appear.
Select Edit Bot
Once you have selected one of the options, all you have to do is write the text you want to add to the sections of your profile or, in the case of the profile picture, upload the photo you want to show to your customers.