I have attached the EBS volume to the EC2 instance (running Galaxy). I now need to mount the EBS volume to the EC2 instance. To do this I will use Putty to make the connection. But first I have to convert the private key from ".pem" format to ".ppk" format. I am trying to use Puttygen for the conversion, but the ".pem" file is not recognized and I get this error message:

Could't load private key (key file does not begin with OpenSSH key header)

Does anyone have experience with this?

BTW, I am using windows.

Thanks! 
Cheers,