thanks for excellent response time. didnt know you could do this, but it worked with "gksu gedit"
However, how do I change settings for a hole directory? I want to create a new directory in /var/lib/tomcat6/webapps/ .
I can not right click on it in the ubuntu explorer; and also in a shell chmod 755 tomcat6/ does not seem to work.
You should not attempt to modify server.xml for webapp contexts. That is discouraged since at least Tomcat4, and we're on Tomcat 6 or 7 now. There is a special directory designed to hold Context definitions, or you can put the Context into a file named META-INF/context.xml in the WAR.
You should very definitely not attempt for applications to write files anywhere within the Tomcat directory tree, and that includes anywhere within or under webapps. If you're attempting to copy a WAR file or exploded WAR directory under webapps to deploy it there, you'll need write access rights. If you cannot obtain access rights, you can use the Tomcat manager webapp to upload the WAR, if you're authorized to use it, or you can leave the webapp outside of Tomcat altogether and point to its location using the Context and an absolute path. If you do that, Tomcat has to have read access rights for that location, of course.
An IDE is no substitute for an Intelligent Developer.