How to create key-pair in OpensStack dashboard?
Open Compute -> Access & Security -> Key Pairs
Click "Create Key Pair" and insert the name of the key (eg. "john-doe-key")
Save the private key on the disk
Locate the private key on your disk
Copy the key to the place of your choice (in linux the keys are usually kept in ~./ssh
Click on "Accesss & Security". You will see the public key stored in OpenStack.
You can now create instances using that key.