This tutorial will show you how to configure linux machine to allow you to log into this machine using SSH key pair.
Login into linux machine where you want to enable ssh key pair login for particular user.
In that user's home directory create directory .ssh
Replace [username] with user name of that user.
Copy file with SSH public key to that server. This file may be named like 'id_rsa.pub'.
append content of that file to file .ssh/authorized_keys
cat id_rsa.pub >> /home/[username]/.ssh/authorized_keys
Server is now configured to allow you to login via SSH key pair.