How to attach a source library (jar) to a web/ejb project?

The two folders:

I'm confused about jar attachment. I can place them into the /src/config/lib or into the /web/WEB-INF/lib folder as well. When should I copy my files where? What is the difference between the two solutions?

Namespaces:

In my web project I put the /src/config/lib folder into the "Source package folder" but the namespaces (for RichFaces) do not appear as suggestions at namespace definition (xmlns:a4j= + ctrl-space) in NetBeans. How can I make them visible in the list?

I put this files into the /src/config/lib folder:

richfaces-a4j-4.5.17.Final.jar
richfaces-core-4.5.17.Final.jar
richfaces-page-fragments-4.5.17.Final.jar
richfaces-rich-4.5.17.Final.jar
cssparser-0.9.18.jar
guava-19.0.jar
sac-1.3.jar

Its documentation says that it is enough for accessibility.