Hi @SudeepGarg
Integration is straight forward. Highlighting sequence of steps you can follow
1. Setup google ad manager and generate the ad tags
Follow this tutorial https://www.youtube.com/watch?v=O6g9-y8PgnI&t=42s
2. Create a clientlib in aem to include the GTM javascript files and any customjs required
Copy the required script from google ad manager and paste it in the clientlibs
3. Load the clientlib as part of your template / create as a custom component that can be used anywhere you want to shows adds
Hope this helps as a starting point