Nios Eclipse Problem IORD e IOWR

I'm not familiar with that IP core, so you'll have to carefully read the documentation for specifics. The pins are mapped in your top level HDL or schematic file to your Ethernet hardware. I think what you are trying to ask, though, is "how do I write to the Ethernet controller?" IORD and IOWR are probably not what you want. These are very basic low level Nios instructions. You should instead use whatever driver comes with the controller. The documentation will tell you what header file to include and how to setup and control the ethernet controller.