Small Office Network Setup Help

Hi folks,

We are renting a small office in a floor which consists of many offices. The way internet is distributed here is, they have a verizon fios router and a couple of unmanaged switch, from which cables are run to offices for internet. One of the port on a switch is dedicated to our office.

In our office we have 6 computers and a network printer. The computers need to share files with each other and be able to print.

We want to isolate our office network from others. When we use an unmanaged switch, the version router dhcp assigns ip addresses to computers and we are able to access the internet. The verizon local ip is: 192.168.1.xxx. But we can also see computers that are of other offices, which means they can see us.

How do we create a separate network? Say we want to use  IP 192.168.10.XXX or 10.0.0.xxx. We just bought a Dell 24 port managed (L2) switch.

Thanks