I want to use Splunk app for aws to monitor my aws instances. For that reason, I want to add my aws account to Splunk app for aws, but when I go to configure section of "Splunk app for aws" I don't see a place/section to add aws account information.
You need to add the Splunk Add-on for AWS to setup your credentials and inputs. You can either use your Access Key / Secret Key for the credentials, or you can grant your AMI access via an EC2 role. The second option is if you are running the AMI in your AWS deployment.