want to activate Disk Usage and Ram Usage metrics

You can find instructions on installing the CloudWatch Agent on Windows here: https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/install-CloudWatch-Agent-commandline-fleet.html

The install steps cover downloading the MSI for Windows (step 1) and installing it with msiexec (step 3). You will need to attach a suitable IAM Role to the instance, but the steps for this do not depend on the OS. Finally, instructions for starting the Agent are at the bottom of the page.

After it's installed, you can follow the steps for configuring it, which also cover Windows hosts: https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/create-cloudwatch-agent-configuration-file.html