JRE system Library [jre7]
The import org.jdesktop cannot be resolved
Build Path > remove from build path
project > properties > java build path > add Library > JRE system Library
org.jdesktop code is not part of Java SE, so the classes won't be in the JRE. You need to locate and download a JAR file containing the classes, and then add it to your Eclipse buildpath.
(One place to download the JAR is here ... but it is easy to do your own searching if this link breaks. Go to Maven Central or findjar.)