Networking is a large combersome subject. Don't let that discourage you though! Knowing the theory behind networking will allow you to understand it's implimentation and uses.
First, the theory of networking is broken down into two parts: Data and Clock Control. We will start with the first and easiest of the two, Data.
Data is only ones and zeros. that is all it is. How you use or what significance you give those ones and zeros is what determines what your network is capable of. If broken down one can see that the computer itself is a network. the harddrive, motherboard, ram, and processor all work together to perform a function based on the data given to it. Data thought to be a command will be used as a command wether or not it was actually a command. A number used like a string will also return no error. Data is Data, nothing more. What counts is how you use it. So when developing your network system make sure to keep in mind what it will be doing and how it will accomplish it.
Clock control is all important in networking! You absolutly need a clock when networking in order to coordinate messages between computers. Two computers with two seperate clock speeds will not cooperate correctly unless There is a speed converter between them. The two types of clock control are: independent, and dependant.
Independant means every computer has it's own individually running clock. This is what real world computers use and this systems has some uses but poses some problems for begginers.
Dependant means there is one central clock that runs all the computers. This leads to flawless trensmission every time but poses a problem with space and expandability as two wires must be ran instead of one.