setting up network with roadrunner

this is probably easy but my brain wont function.
i just started a new job and they have a small network running. they set it up with a domain and assigned ip’s to get an application to function correctly. they have roadrunner and want the remainigmachines that are using this application with assined ip’s to have internet access. they have a linksys router and the remaining machines and server are running dhcp.whats the easiset way to setup the network to have internet access.i attempted to put the routers gateway in tcpip and no go. what would be the easiest and correct way to set it up even if i should reconfigure everything. thanks