Assign valid IP addresses to virtual machines

Hello every one,

First of all I wanted to mention that I'm totally new to this virtualization thing and forgive me if this is a dumb question, but I'm really confused about that. So I have a dedicated server with 5 valid IP addresses that clearly one of them is used for the host (the mentioned dedicated server), now I have 2 virtual machines on this host and I need to assign each machine a valid IP address, Can you please tell me how can I do that?

Thanks in advance