Hi Anessa,
If you are providing a pre-determined list of images in a select box or with radio buttons, then I would set the "value" of those controls to the image name to be displayed, then get those posted form fields (like you do your other fields on the form) and save the image name to the database. Just make sure you combine the image name with appropriate path information when showing in your web page.
If you want them to upload their own images, then that is a different story. You will need to use components like ASPUpload to manage the uploading and saving, and be able to set permissions on your web server appropriately.