When you’re launching tomcat server from netbeans IDE you need to check in menu “tools->servers” on connection tab for tomcat server – there is catalina base directory. And you need to include something like:
<role rolename="manager"/>
<user username="admin" password="admin" roles="manager"/>
at file
\CATALINA_BASE\conf\tomcat-users.xml
or use username automatically generated by IDE with description already placed in this file or on connection tab
For Manager Apps : GUI access:
<role rolename="manager-gui"/>
<user username="tomcat" password="s3cret" roles="manager-gui"/>