When you create an EC2 instance or receive access details to your server / instance from our support you also receive a private key file ( with extension: *.pem). It is actually a certificate in a format called “Private Enhanced Mail”.
Accessing your server with Linux / Unix ssh or scp clients is done simply by adding "-i keyname.pem" to the command. for example:
ssh -i ServerAccessKey.pem firstname.lastname@example.org
In MS windows however you need to use putty utility available from here. Putty does not support pem files, instead they need a ppk file that can be generated by using a Puttygen utility.
Download here and run Puttygen.
From the menu tab “Conversions”, use “Import key”
In following dialog, locate relevant pem file and open it.
Create PPK file by clicking on “Save private key” with a name you want to use.