Once the EC2 instance is launched and is confirmed to be in the Running state, you can now connect to the instance using either an SSH client for Linux or Remote Desktop for Windows, depending on what kind of EC2 instance you have launched. For SSH connections, you must ensure that port 22 in allowed in the security group. Remote Desktop uses port 3389 for connection. 

For logging into the EC2 instance, you will need the public DNS name or IP address of the instance. You also need the private key for Unix instances and Administrator for Windows instances. The Administrator password can be easily obtained by invoking the GetPasswordData() function.