You have two routers. likely you have DSL (most dsl modems are routers)

Internet----207.24x.xxx.xxx----router1----10.3x.xxx.xxx----router2----192.168.xxx.xxx----pc

You can do several things
(1) Dump the router2, plug into the router1 (if its got ports free)
(2) Take the cable from router1 to router2 and plug it into the LAN side of router2, and disable dhcp on router2, as router1 well do it, (router2 becomes a hub/switch)
(3) look in router2 status screen, near where you see it says its internet ip is 10.3x.xxx.xxx and find its GATEWAY, this is the IP of router1, you must forward needed ports from router1 to router2 and from there to the pc. (if everything is behind router2, then u could DMZ router1 to router2's ip)


Ps; be aware that both ranges 10.?.?.? & 192.168.?.? are LAN ip ranges and dont appear on the internet, they are reserved for your lan, my lan and dat guy over theres lan. in other words we can all use them becuase they arent anywhere but in our own lan.