To set up your development environment, begin by starting Flex Builder 3. When the Workspace Launcher dialog box appears (see Figure 2), enter the directory to use for your workspace. For example:
C:\ADC\Workspace

Figure 2: The Workspace Launcher
If the Welcome page (see Figure 3) is open when Flex Builder starts, close it and go to the workbench.

Figure 3: The Flex Builder welcome page
As an optional step, you can update the Java Runtime Environment (JRE) to the most recent version. This is not a necessary step; Adobe Flex Builder ships with JRE 1.5.0_11, which will work just as well with the sample application. To do this in Flex Builder, follow these steps:
Choose Window > Preferences. On the left hand side of the Preferences dialog box click Java and then Installed JREs. Click Add to add a new JRE (see Figure 4).

Figure 4: Installed JREs
Select Standard VM and click Next (see Figure 5).

Figure 5: Selecting the JRE Type
Click on Directory and browse to the desired JRE directory (see Figure 6).

Figure 6: Add JRE Dialog
Select the checkbox in front of the newly added JRE and click OK, then click OK again to close the Preferences dialog box (see Figure 7).

Figure 7: The newly installed JRE
It helps to create the server runtime before you create the actual project so that you are prepared when the New Project wizard asks you to select a server. Choose Window > Preferences. Next, on the left hand side of the Preferences dialog box click Server then Runtime Environments. Click Add to add a new runtime (see Figure 8).

Figure 8: Server Runtime Environments
Expand Apache, select Apache Tomcat v6.0, and click Next (see Figure 9).

Figure 9: New Server Runtime Environment
Click Browse, browse to the extracted Tomcat directory (in this case, c:\ADC\apache-tomcat-6.0.18), and then click Finish (see Figure 10).

Figure 10: New Tomcat Server
Click OK to close the Preferences dialog box.
To create a new server, right-click in the Servers view of the Java EE perspective and select New > Server. In the New Server dialog box, select Apache Tomcat v6.0 Server and click Next (see Figure 11).

Figure 11: Define the Tomcat Server
For now, do not add or remove any projects (see Figure 12). You will add the Web application to the Tomcat server later. Click Finish.

Figure 12: Do not add add and remove projects in this step.