I have configured a network environment, as below screenshot. Now I want the laptop n5 to connect to n10. When I run the traceroute command, it shows that the n5 can only reach to router n8. How can I let the router n8 connect to the router n1?
You either need to run a routing protocol between the two routers so that they can share routes, or you need to put static routes on each router pointing to the other router for routes on the other router.
Static routes don't scale. Using a routing protocol can automatically share routes.
You will probably learn RIP first. Something like this on each router:
router rip version 2 no auto-summary network 10.0.0.0