This is harder. Remember, to truly represent a relationship you need to make sure that the appropriate foreign keys are in place in the schema to allow joins between tables. However, every time you construct a new query involving these tables you will need to specify the appropriate join conditions. Even if you define foreign keys, Oracle will not figure out the joins for you. This makes the relational model very flexible, but also makes queries hard to write for the novice.
All relationships turn into foreign keys.
Some of them also turn into an extra table. They may also turn into not null constraints. This is the most basic use of a foreign key. It may make sense to rename the foreign key to reflect its relationship to the table you are inserting it into. Ask yourself whether it makes more sense to leave this as two separate tables, or to join them together to make one big table.