Beatdigital

1. Open Flex-Builder and choose from the menu Help->Software Updates->Find and Install.
2. Select "Search for new features to install" and click Next.
3. Click on "New Remote Site", enter a name (e.g. PDT) and paste, in the URL section, the following address: http://download.eclipse.org/tools/pdt/updates .
4. Select two checkboxes:
   1. Europa Discovery Site and
   2. PDT
   (The europa site was added so that required plugins which PDT depends on can also be downloaded.)
5. Click Finish, choose a mirror site and wait for the search results.
6. In the search results:
7. Select the PDT checkbox
8. expand the Europa Discovery Site
9. click on "Select Required" button.
   Now all required features should be automatically selected.
10. Click Next, Select "I accept...", click Next and at last click Finish.

To see if it's installed OK, you can try File->New->Other.. and look for PHP project under PHP section,