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.
Click OK.
This will add your UserCfaNo to the database.
Let me know if you still have any other questions.