The first step is to create a key pair on the client machine (usually your computer):

ssh-keygen

output will be something like

Output Generating public/private rsa key pair.
Enter file in which to save the key (/your_home/.ssh/id_rsa): 
that is the location where the stored 

Next step will be

ssh-copy-id username@remote_host

and password will be asked, insert password
and you are good to go.