Retrieving samples from an FPGA using Ethernet
You will need to push packets out of your FPGA using a block of HDL code which implements at least some of the Ethernet protocol.  

If you limit yourself to a point-to-point link, then you should be able to write something fairly simple which will just generate broadcast packets with your data in.

You can then work up from there to a more conventional network where you respond to the ARP request from the PC, maybe accept some packets for configuration, and address your data specifically to the host rather than broadcasting it.