Apache Tomcat Version : 6.0.18
Open the tomcat-users.xml, located in your Tomcat Home/conf folder.
To add a role :
<role rolename="myRole"/>
To add a user :
<user username="myUsername" password="myPassword" roles="myRole"/>
To asign multiple roles to a user :
<user username="myUsername" password="myPassword" roles="myRole1,myRole2,myRole3"/>
tomcat-users.xml
<?xml version="1.0" encoding="utf-8"?>
<tomcat-users>
<role rolename="manager"/>
<user username="admin" password="admin" roles="manager"/>
</tomcat-users>