Since you have DataAssist, the update should be easy.
In Dreamweaver open the Server Behaviors Panel (Window -> Server Behaviors)
You should see a "Insert Record (users)" in the list, double click the entry
When the wizard open, click next, and your added entry should show i the list. Select UserCfaNo and bind the value to your form element.
This will add your UserCfaNo to the database.
Let me know if you still have any other questions.