Method 1 - use the same keys on the servers:

Convert the keys to openssh format and upload the private keys to the servers. When you ssh to the destination host, specify the private key file:

ssh -i mykey.pem private.ip.of.other.server

Method 2 - Create new keys

On each server run:

ssh-keygen

Hit enter enter enter. You'll have two files:

.ssh/id_rsa
.ssh/id_rsa.pub

On Server A, cat and copy to clipboard the public key:

cat ~/.ssh/id_rsa.pub
[select and copy to your clipboard]

ssh into Server B, and append the contents of that to the it's authorized_keys file:

cat >> ~/.ssh/authorized_keys
[paste your clipboard contents]
[ctrl+d to exit]

Now ssh from server A:

ssh -i ~/.ssh/id_rsa private.ip.of.other.server

Method 1 - use the same keys on the servers:

Convert the keys to openssh format and upload the private keys to the servers. When you ssh to the destination host, specify the private key file:

ssh -i mykey.pem private.ip.of.other.server

Method 2 - Create new keys

On each server run:

ssh-keygen

Hit enter enter enter. You'll have two files:

.ssh/id_rsa
.ssh/id_rsa.pub

On Server A, cat and copy to clipboard the public key:

cat ~/.ssh/id_rsa.pub
[select and copy to your clipboard]

ssh into Server B, and append the contents of that to the it's authorized_keys file:

cat >> ~/.ssh/authorized_keys
[paste your clipboard contents]
[ctrl+d to exit]

Now ssh from server A:

ssh -i ~/.ssh/id_rsa private.ip.of.other.server