One column link to others
Decide which you type of "relationship" each "link" is:  "1:1", "1:many", or "many:many".

1:1 should be represented by having the columns in the same table.  (There are exceptions, but you aren't there yet.

1:many is implemented via an id of the "1" in the "many" table.  Example:  A person owns "many" cars.  The cars table has a column person_id to say who it is owned by.

many:many needs an extra table with ids of both of the tables.  Example:  students and classes:

CREATE TABLE WhoTakesWhat (
     student_id INT UNSIGNED NOT NULL,
     class_id INT UNSIGNED NOT NULL,
     PRIMARY KEY(student_id, class_id),
     INDEX(class_id, student_id)
) ENGINE=InnoDB


I encourage you to be thinking in terms of SQL; you will eventually have to use it.

Meanwhile:

A "database" contains several "tables".
A "table" is a set of "rows" and "columns".
"Columns" tend to be dissimilar (id, name, date, ...)
"Rows" are different instances of what is being stored in the table (various "students" in the table named students)