Tier II account can be opened along with Tier I or it can be activated later either online or by visiting POP.
Contribution to NPS is very simple. You may choose any of the options explained here to contribute to NPS.
Tier II account is a voluntary account under NPS aims to provide liquidity to the Subscriber to meet day-to-day need/financial contingencies.
Subscribers can avail the these services online (through log-in or using Aadhaar based/Mobile based authentication)
Subscribers can perform these functions via the NPS App (available in “Google Play Store” as “NPS by NSDL e-Gov”) on the go.