internal LAN connectivity without internet

I have a small doubt regarding the LAN as i Havesome pcs in my office i want to connect them internally with the little cable connection but i don't want to use any internet activity from them.(purpose is the share the data internally and no use of internet).

And i have some more selected people who want to use the internet access so i want to give some special access for internet for that selected laptops.

Iam a kid in networks as i don't have any idea how i can start and move with the project suggestions are mostly accepted

You can do the following :-

1. Establish a small LAN connection in your office which will consist of those selected PC's which are not intended to run internet at all! You can simply establish LAN connection using routers and switches! Then,develop a small web-server like thing on one of the PC's which will work as server and the rest will work like clients! You can simply set up a distributed server which will take care of synchronisation things too(but, that is not advisable for a basic OR a newbie)!

But, simply multiple-clients and a server is what you need to establish using LAN connection for and make network file-sharing access permissions for all the systems... There are several softwares to transfer files and internally communicate like a small mail-server intended for OS like Windows,Linux,etc.

1. Next for those laptops which you wanna connect to internet---please establish a source of internet like any ISP and so! Next,a gain establish a small LAN connection among those PC's which you want to connect to internet to. That's it,VOILA!

Next step of yours would be simply to configure DNS setting,IP-Address of the ISP,Subnet Mask and Gateway and that is damn easy. You simply need to add it to the router settings through which all of your systems,which are intended to access internet,would be connected. If you want to achieve the first thing with these PC's, then simply establish a local web-server or mail server for file transfer or mails,etc. locally within the office.

Another possibility :-

Establish the web server communication with all the PC's connected. Connect all the PC's and laptop to router's and switches as desired. Keep a note of IP-Address of all the PC's and laptops. Now, install a web-filter/firewall which will restrict users from accessing internet based on their hostname & IP-Address. Remember for this to take place, all the systems must have static IP-Address allocation,not the DHCP configuration!

I guess these are some of the possible steps. But,there can be several effective steps too...

Best wishes from my side!