i you want to start learning network u need understand the introduction of the network.
try to do these steps :
1. operating system ( XP , 2000 & 2003 ).
2. protocols ( TCP , UDP & IP ).
3. Topology ( Bus , Start , Mesh etc. ).
4. introduction of networks. ( INTRO )
5. interconnecting networks ( ICND ).
i suggest before u start learning the Intro try to read A+ and Network+. finally u have alot of work mate.