Dunno what router model you have. Many info can be found searching the Cisco site.
http://www.cisco.com/en/US/products/sw/secursw/ps5318/prod_installation_guide09186a00803e4727.htmlThis might help:
Step 1 Enable the HTTP and HTTPS servers on your router by entering the following commands in global configuration mode:
Router# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)# ip http server
Router(config)# ip http secure-server
Router(config)# ip http authentication local
Router(config)# ip http timeout-policy idle 600 life 86400 requests 10000
If the router supports HTTPS, the HTTPS server will be enabled. If not, the HTTP server will be enabled. HTTPS is supported in all images that support the Crypto/IPSec feature set, starting from Cisco IOS release 12.25(T).
Let me know if it works. Otherwise try to find some Cisco books.