How to connect to a launched running EC2 instance....read AWS documentation for latest
....it depends 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)