Any help or a step by step instruction document will be helpful
You can follow the tutorial Install Ops Manager on Windows for Windows step by step installation.
Please note that OpsManager is part of the MongoDB Enterprise edition, which is a commercially supported product. If your company already has a commercial subscription and you have further questions about installing/running OpsManager, I would suggest to open a ticket in MongoDB Commercial Support Portal.
Alternatively if you are evaluating MongoDB Enterprise and interested, feel free to privately contact me with your contact details and I can request a MongoDB Account Executive to contact you.