Create a Discord account and log in
Go to the Discord Developer Portal
Click New Application
Enter a name for your application and create it
Open the Bot section
Click Add Bot
Confirm by clicking Yes, do it
Copy the bot token and keep it private
Set the bot username and avatar if needed
Go to the OAuth2 section
Open the URL Generator
Select the bot scope
Select any required permissions
Copy the generated invite link
Open the invite link in your browser
Choose the server you want to add the bot to
Click Authorize
Complete the verification if prompted
If you are the server owner or have Manage Server permission, the bot will be added
Start the bot code or hosting service so the bot comes online