You can find answers about next steps after naturalizing here:
https://www.uscis.gov/citizenship-resource-center/new-us-citizens
In short: update status in SSA, notify employer, also get passport.
The reason to get passport (and card ID) is to have additional proofs of your citizenship. Also, it takes months to get US passport, so it would be a good idea to get it done sooner. You are required to leave and re-enter USA on US passport.