You do not need to manually type in the name of the image, in your DataAssist insert you should expand the Upload File bindings and for the file name use the lightning bolt icon to select the server file name from the upload bindings. This will automate the insert so that when a new image is uploaded a record will be inserted and the name of the just uploaded image will be inserted into the record.
When you want to view the image you just need to have a recordset that selects that record from your db, then put an image field on the page and set the source to the folder the image was uploaded to. For the file name within the src attribute of the img tag use the filename binding from your recordset.