Here is some sample code that shows you how to enumerate the EC2 instances currently associated with your AWS account.
DescribeInstancesResponse resp = ec2.DescribeInstances(new DescribeInstancesRequest());
DescribeInstancesResult result = resp.DescribeInstancesResult;
foreach (RunningInstance inst in result.RunningInstance)
Watch this space for more snippets of code that will help you manage your AWS resources using the SDK for .NET.