By default in a Linux EC2, allows authentication using a KeyPair, so use a KeyPair to login to the EC2 instance and then follow the below steps:
Step 1: Run the below command from the EC2 Linux prompt to add user praveen
sudo adduser praveen
Step 2: In the /etc/ssh/sshd_config set the property PasswordAuthentication to yes from no. This has to be done as a sudo (administrator).
Step 3: As the ssh configuration file has been changed, restart the sshd daemon using the below command.
sudo service sshd restart