How can I access tomcat's admin pages?

[Batsheva Raviv]

I have 2 questions:
1. How can I access tomcat's admin pages?
2. When ever I try the to execute the following URL :
http://braviv:8080/admin/contextAdmin/contextAdmin.html, a window pup up
with the message "Enter Network Password".  Please type your user name and
password.
The window print also site:braviv,  Realm Admin
does anybody know what should be the user name and the password.
Batsheva