How to apply subnets(subnetting) to real world switch/router?

What I mean by that is let say company wants to have 4 networks on their class c ip. We do the math, we subnet ip to four(4) networks and now what? I mean how would we apply it to the hardware? Let say I have a switch with 100 ports...should I just create 4 VLANs i.e 25 each and in each vlan I would apply specific ip range/subnet mask I came with while subnetting? OR should I do something else? Thanks in advance for any resource.

Regards,
ketrab