OH this is a joke, right?
With an active directory or a workgroup?
Do you have a domain controller?
How many groups are there, and do you wish to control services offered to each group based on their roles?
Is there cables to each workstations? Does each workstation have a NIC? What operating systems are the clients (that is what the PC that access the network are called BTW!)?
Should all workstations have internet access?
Do you have DSL or CAble for your ISP? What firewall are you planning on deploying? Does each client going to house their own internal virus protections? How are you Planning on supporting updates?
This is a joke, right? It has to be a school project then, in that case, we don't help!