ETHERNET communication on PIC micro-controller, where to start?
What you ask for is doable.  But, since you're talking about "doing Ethernet", asking whether it's similar to RS-232, and your research consists of reading "some PDFs", this is currently way over your head.  You are going to need someone that knows what they are doing for this project.  If you're smart and attentive, you can learn from this project and maybe do it yourself next time.  Do not try to do this on your own with your current level of knowledge and inexperience with Ethernet and networking in general.

Just to give you some idea, Ethernet is only the low level physical layer to get network packets from one place to another.  Most likely, your "Ethernet" requirement really means networking using at least TCP/IP and or UDP/IP.  There is considerable complexity in this, and it requires a network "stack" running on the micro.  Even then, you have to know what you're doing at the application level to use such a network stack.

Hardware wise, all you need is a PIC 18F67J60, the Ethernet pulse transformers, and a RJ-45 jack.  That PIC has a Ethernet MAC/PHY built in, and there are various network stacks available for it, including my own.  However, there is much much more to "doing Ethernet" than just hooking up the hardware.