If you have applied the upload behavior using CSS Form Builder, double click the Insert Record server behavior. Click Next button to go to Step 2. Find your file field in the Insert values list. Click to highlight. Now click the lightning bolt button to the right of Value. You should see your Upload Files section for your file field. Expand the list and choose Server File Name. Click ok and then click Finish. This should now insert the file name of your image in the database.
Remember when wanting to display the image either on the following Details page or otherwise that you must include the path to the upload folder. Good luck.