How can I send data (bits) from a port to a circuit?

We are working on a visible light communication (VLC) project and we have a circuit built that can transmit and receive data through an optical link. Now we want to use PCs to send actual files (an image for example) by connecting the transmitter's circuit to a PC and the receiver's circuit to another PC.

How do we, using matlab, send an image as a stream of bits (ones and zeros) through the ethernet port? How do we access the physical port through matlab and use it to transmit a stream of bits?

Regards