What do you mean with the RJ45? Control LED over the network? Why not use the communication port or usb to comm adapter then make a little app with c# or use hyper terminal to make more simple.
the best option for me to connect to pc is, connect with RJ45 kable to router or direct to pc because i also need to control it with different devices over the internet or at home
can you please let me know where to search and how?
You might search on "ethernet port board". Here are a couple of items that might be useful -
**broken link removed** https://www.sparkfun.com/products/10536
The first ones about $100, the second is about $50. They bother require some programming. Unfortunately, what you are asking is not a simple task!