The Network has a utility token which allows for the exchange of storage, bandwidth and compute resource between node operators and users wishing to store data on the Network.
It's the financial incentive for node operators to join the Network and cooperate toward the goal of providing secure data storage. Conceptually this is similar to that of Bitcoin: to ensure that cooperative participation is a more rational course of action than uncooperative or malicious activity.
Tokens can also be transferred directly between users and used as a means to pay third parties for goods and services.
When a user of the Network requests a file, it uses the data map (which may be held locally or stored somewhere on the network) to identify the component chunks. It then asks the Network for those chunks and the requests are routed automatically to the nodes that hold them. Those nodes then return the chunks and the client uses the data map to decrypt them and piece them back together to recreate the file.