How do I use Time Machine backups made for a dead iMac

My iMac (Early 2009) computer died (probably the graphics card which is no longer made so may not be able to fix it).

It has Time Machine backups. How do I access them from another computer on the same network? When I launch Time Machine from my Mac Book Pro it connects to the separate Time Machine that I have for it. I can connect to the Time Capsule that has the backups but I don't see how to get to and use the iMac backups??