Franz,

Go into your project properties (make sure it's a Java project), and go
to the Java Build Path category and then click on the Libraries tab.

There, you should add in any jars that are included with your project
(Add Jars...) as well as any jars that might be referenced once your
project is deployed (Add external Jars...)

Also, if you are having general package recommendation errors with
Eclipse, make sure that your source folders are set correctly.

As an example, in my Java project, I have a src/java directory that
contains all of my java source. Under project properties -> Java Build
Path -> Source (tab), I added the folder src/java.  That resolves a lot
of package related errors that Eclipse will report when it thinks that
your project root is the base for your Java source files.

Hope that helps
Collin