IP is a layer-3 protocol, and TCP is a layer-4 protocol. Neither protocol understands files. An application will send data to layer-4 (TCP), and TCP will break the data into chunks and encapsulate it in TCP segments. TCP will pass the segments to layer-3 (IP), which in turn encapsulates the segments in packets. IP will pass the packets to layer-2 (ethernet), which encapsulates the packets in frames. Ethernet will then pass the frames to the hardware (driver) which serializes the frames to bits on the wire.
TCP is one of many layer-4 protocols. It is a connection-oriented protocol which creates a bi-directional conversation with TCP on the other end. TCP provides guarantees for delivery and reassembly of out-of-order segments, and this is why it is often used for files transfers, but an application could use something like UDP, which doesn't have any guarantees. With UDP, the application must take on the responsibilities to get all data and reassemble it into the correct order.
This Wikipedia article may help you understand the OSI Model.