Hi @PadmajaS
There are few ways to implement at.js ( Adobe Target library)
1) Using Adobe Tag manager - Adobe Tags
2) without using tag manager - Simply use at.js JavaScript file
3) Implement Target using a third-party tag manager such as Tealium, GTM etc ..
To be start with you can go through below documentation - this shows you the way to deploy at.js
https://experienceleague.adobe.com/en/docs/target-dev/developer/client-side/at-js-implementation/dep...
You can also follow the official tutorial from here - https://experienceleague.adobe.com/en/docs/target-learn/tutorials/overview
Hope this helps. Feel free to post if any more queries you have about this implementation
Thanks,
Gokul