I need help with configuring my linksys router and an asa 5505.

I have an asa 5505 connected to a gigabit smart switch with 15 devices on it one being a server 2008 r2 proving dhcp. I need toprovide Internet access to another office but I’m limited by the basic license of the asa. I want to connect the router between the asa and the switch so the asa only sees one address. Please help. I can provide asa configuration if needed.