I installed Netbeans and tryed to access the server\'s manager using: (id/pass)manager/manager, admin/admin, system/password... None of them worked.
In Tomcat 7 you have to add this to tomcat-users.xml (On windows 7 it is located by default installation here: c:\Program Files\Apache Software Foundation\Tomcat 7.0\conf\ )
NOTE that there shouldn't be ANY spaces between roles for admin, as this list should be comma separated.
So, instead of this (as suggested in some answers:
it MUST be like this: