How to connect to a launched running EC2 instance

....it depens on what you have installed for software on the instance ---but, you can always do the following:

Step 1) log onto aws.amazon.com, on dashboard hit EC2 then, Instances....right click on the instance you want to connect to and select Connect

STep 2) It will give you directions on how to connect --- DO IT (usually with ssh client)

how to setup putty AND convert the key you have created with instance launch to something putty can read https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/putty.html

Here is me logged in after following directions above