Defining Relationships/Primary Keys between two tables

Hello,

I am having difficulty in designing a database and specifically creating the
correct relationships and primary keys.

Right now I have two tables that have several fields, but I have just listed
the fields that I think are important and may be the link between the tables:

tblInternal Jobs
JobCode (primary key)
Grade
GradeCategory
Other fields…

tblPayRanges
Grade
GradeCategory
Other fields…

In tblPayRanges, the combination of Grade and GradeCategory would create a
unique field that I thought I could link then to tblInternalJobs.

When I try to define the relationships so that I can get one to many, it
obviously does not work. What do I need to do to create the appropriate
one-to-many relationship? Or better, what fields should I have and what
links should I make to create the correct relationships?

I am trying avoid creating autonumber fields as the primary key as I
understand that can be problematic. If that is my only option, then I will
do it, but based on my reading, I think I can do it without.

Thanks in advance for your help.