how to create a secure network?

can somebody share me an idea how to create a secure network using 2 router, a hub, a switch, a server and 50 computers?

Give us a synopsis about this network i.e what the network is supposed to handle ?

what kind of servers are you talking about ?

sorry for the incomplete details. So this is the specification of the devices:
server: web server and database
we need to use the xampp as the database
Switch: 2pcs. Cisco Catalyst 2960 cisco (48 port switch)
Computers: 50 pcs. computers
os used: windows xp
router: cisco router 7260

and never mind the hub. It is not encluded. I wish that you can give me more patience because I am really not professional on this field, I am still starting. Just tell me the following:
-what should I implement
-what should I need to add
-where to connect.
-what i need to improve on my network. Or do you have any other suggestions in creating a secure network. I know this is really complicated and I am hoping for your patience. Thanks!

Are you building the network technically?
What is your skill level?

You need a dedicated firewall for the network since you are stressing on security. May be a Linux box like Untangle with three LAN card. one LAN card goes to your Internet connection, the second card goes to a switch that will accomodate your internal network. The Third LAN card will go to your DMZ where your webserver could reside but not your database server. You need to be grounded on Linux to get the security config right .

Alternatively, You could use a cisco pix instead of a Linux box with enbedded software, and a config platform. You also need to b e conversant with the cisco Command Line to get your config right.

If you your skill level is low you better outsource it