1. Enable SSH on the EC2
Click on the security group setting on the EC2 instance

Add SSH rule for the security group / Click Save rules

2. Connect EC2 via Instance Connect
Via EC2 Instance Dashboard, select your EC2 instance / Click Connect

Select EC2 Instance Connect / Enter user name (ec2-user) / Click Connect

AWS will open the web browser to manage your EC2 instance

3. Connect EC2 via SSH Client
Select SSH Client and you will see the guide:
From your computer, change mode for the key pair that you created before. Command: chmod 400 awstraining2021.pem
Connect your EC2 by using the SSH Command

Change mode & SSH

Successfully!

You can try some linux commands on the CLI.