You created an AWS EC-2 instance (aka a virtual machine or server) running Linux. You want to connect to this Linux server (a VM). You created a key pair when you created this VM. You downloaded a .pem file. You need a .ppk file. But you only have a .pem file. What should you do?
1. Download a puttygen.exe file from this location.
2. Open puttygen.exe (nothing needs to be installed).
3. Go to File -> Load Private Key. Find the .pem file.
4. You should get a "PuTTYgen Notice." Click ok to that.
5. Type in a key passphrase in the PuTTY Key Generator in the fields requesting it. Remember this password.
6. Click "Save Private Key." Give it a name that you want.
7. Open the regular putty.exe. Expand Connection -> SSH -> Auth. Near the text field for "Private key file for authentication" field, click the "Browse" button. Open the .ppk file you just created.
8. In Putty go to the "Session" field. Then click on "Host Name." Enter the IP address of the EC2 instance you just created. Click "Open."
9. The username will be ec2-user if the server is running RHEL or SUSE. If the server is running Ubuntu, the username will be ubuntu. The password will be the one you entered in the step that created the .ppk file.