Fei Li,
At this time importing existing projects is a fairly manual process. You first need to figure out all the EJB and Web modules that make up your enterprise application. Then you need to create each individual module as a new EJB or Web project in MyEclipse and import the artifacts from your existing projects manually (Drag and drop). After that you can create an Enterprise Application Project and add all those EJB and web projects to it as modules. Then you can deploy your EAR and it will package all the individual modules.