Spanning Tree Protocol (STP) has nothing to do with routing (sorry SMASPE). You should simply have a gateway defined in your TCP/IP properties. The gateway would be a router that is directly connected to the local area network that your workstation is on. Hopefully this router knows how to get to the desired destination (that’s what routers do), but if it doesn’t, then this router (or some other downstream router) needs to be configured. Simply put, routers in the same autonomous system usually exchange routing information via dynamic routing protocols. If configured correctly, the routers will make the appropriate connection for you.