If you could add the relationships to my database for me, that would be great.
Ah, but that is the point of my earlier discussion. YOU are the subject-matter expert. When you study Database Normalization you would learn about table design including cases where you have tables that are related to each other by having a parent/child relationship. (More precisely called a one-to-many relationship.) When you explore the data you have, that is when you consider how each element relates to each other element. We can't tell you how you want to relate things if you happen to want to do something differently than we might have imagined. And that is key to understanding this situation. YOU are plucking this DB out of YOUR imagination, which we don't share. We aren't mind readers. (I left my mind-reading turban at the dry cleaners and they lost it.)
I can show you how to think about relationships but I can't - and shouldn't - actually build the relationships for you. Suppose for this example that you have three tables to consider: a table listing students, a table listing classes, and a table listing a student's class grades. You want to somehow relate them. Here's the approach.
The Students table would include a student ID number of some sort, one unique ID number per student, and it would refer to that student and no other for the life of the database. The Classes table would have a class ID of some sort. Again, the ID refers uniquely to the given class. At the moment we are focusing on grades, not in class enrollment, so remember that this is a case of narrow focus. The enrollment issue is different than the grades issue. That narrowness of purpose is an important part of relationship design.
The grades in the Grades table would relate to a particular student in a particular class. So by this discussion, you realize that there must be a relationship between students and grades and also between classes and grades. That could be tracked by having a Student ID and a Class ID (and probably a date or semester number or six-weeks period number or whatever) for each grade being recorded, presuming you were tracking incremental grades for various parts of the class. The Student ID and Class ID would each be the basis for relating the grade record to the student and the class.
You would define a one/many relationship between the Students table's Student ID field and the Grades table's Student ID. You would define a one/many relationship between the Classes table's Class ID field and the Grades table's Class ID. In the Students table, that Student ID would a PRIMARY KEY (which we abbreviate as PK). In the Grades table, the same field is a FOREIGN KEY (FK) because it is a Grades table field that identifies a record in a table other than (foreign to) the Grades table. By that same standard, the Class ID is the PK of the Classes table but an FK in the Grades table. The relationship is to say that [Grades].[StudentID] points to / links to / depends on [Students].[StudentID] and because a student gets many grades during a class, the relationship is one (student)/many (grades). The Students table is an Independent or Parent table and the Grades table is a Dependent or Child table.
It IS theoretically possible to have a one/one relationship, and Access will actually support that, but I will simply advise that if you think you have a one-to-one relationship between two tables, the odds are that you have overlooked something. It is not that one/one relationships are wrong, but a true one/one is VERY rare and often difficult to manage because of certain potential side-effects. So when searching for relationships, expect to see several one/many cases.
In order to better understand how you would USE these relationships, you need to read a few articles on the subject of JOIN queries, because that is the name of the method that exploits relationships. Access uses formal (i.e. declared) relationships to help you build queries and reports more easily. You will have a learning curve here and I can't soften than blow. Access is not a trivial program (which I'm sure you are discovering) and you must expect it to take a while to understand what you are doing.