Basic Authentication with Tomcat

[Impac7]

Hello.

I have problems converting this 
http://wiki.apache.org/xindice/BasicAuthentication manual from Jetty to Tomcat..

First point "Configure users and roles in the servlet engine": I can't find a 
in realm.properties file in Tomcat. Where do i have to create such a file or is there 
already another File i have to edit? What ist the tools/jetty/conf/main.xml file in 
Tomcat?

Last Point "Configure Xindice XML-RPC Driver (Client side)" What do i have to 
do where?!

I am using: Windows XP; j2sdk1.4.2_04; xindice 1.1b4; Tomcat 5.0.19

I would appreciate any help and please remember I'm not experienced at all with 
this stuff.

Thanks in advance.

Thomas