If you want to set the JRE, you can do it by selecting Window → Preferences.

Figure 16.5. Setting The Java Runtime Environment

After clicking the option, you see the following window:

Figure 16.6. Preferences Wizard

Now you must expand the Java item and select the Installed JREs item as shown above. If you have installed JRE 1.6 already, you will see the following window:

Figure 16.7. Installed JREs Wizard