Plan and design a local area network

Designing a LAN. Well you could go to: http://www.practicallynetworked.com
for some good advice.

When desiging anything consider. Who, when, where, why, what.

A LAN is a Local Area Network which means basicaly all the pc's will connect to a server in the same building/location.

How many users, what type of cables, How fast the server will need to be, how many pc's can physically be connnected to the server for it still to work etc.
Then there is Internet access, security etc. These are just some starting questions you may want to enquire about.

HTH