[news.eclipse.newcomer] import a class from another project

[cool_go_blue@xxxxxxxxx (Williams )]

I created a Java project A. And under A, I would like to import a class 
from another project B which has a package 
org.eclipse.example.Myprogram.ClassA. But when i write
import org.eclipse.example.Myprogram.ClassA, I get the following msg:
org.eclipse.example cannot be resolved.
How should I fix the problem? Thanks.
Will