Discord bot won't respond to my commands

Hello there! I’m new to creating and developing Discord bots. and I created a simple script:

import discord
import os

client = discord.Client(intents=discord.Intents.default())

async def on_ready():
    print('We have logged in as {0.user}'.format(client))

async def on_message(message):
    if message.author == client.user:

    if message.content.startswith('$hello'):
     await message.channel.send('Hello!')


And when I run it in console, it doesn’t give me any errors, and it says that it’s running, and Discord says that my bot is online.

Thank you for reading.