first select the AvailFile text box, the use the delete key to delete it.
go to Insert -> Form File Field to add a file field, set the name of the file field to "AvailFile"
next to the File field, add a hidden form element named existingAvailFile. in the property inspector, click the lightning bolt next to Initial Value and select the AvailFile column from the recordset
you will need to delete the Dreamweaver update record behavior from the page. Go to the server behaviors Panel (Window -> Server Behaviors) Select the Update Record behavior, and click the minus button to remove it.
Next add the upload File Behavior (Webasssist -> File Manipulation -> Upload File). On the second step of the upload behavior, click the lightning bolt next to Default File and select the existingAvailFile hidden form element.
Now add the Data Assist update record behavior, in the server behaviors panel, click the plus button and select DataAssist -> Update Record _ Update Single record
For the key column, select the AvailID column, next to the value, click the lightning bolt and select the AvailID Form Element.
On the second page, click select each column (except the AvailID column) and click the lightning bolt next to value and select the corresponding form element.
for the AvailFile column, expand the WA Uploaded Files (AvailFile) Binding group and select the ServerFile name binding.