Do you know how to work with portals? This is a basic layout object frequently used to manage multiple related records so it is used in nearly every FileMaker database.
Say you are managing photos of your products and may have from 0 to many photos of each product on file.
You might have this relationship:
Products::__pkProductID = Photos::_fkProductID
See the first post of this thread: Common Forum Relationship and Field Notations Explained if this notation is unfamiliar.
Then you'd define your container field in Photos and you could use a portal to Photos on a Products layout to insert as many photos as you need for each given product. This approach is good for inserting new photos a few at a time. Other methods may be needed to load Photos with your images if you have a large folder of images that you want to import into your database all in one batch operation.