How do I find a linear relationship in a table? I really need help on this. And this is at a 7th grade level...

Well, graph it and see if they lie on a line.

or
say I have x and y in columns
take the first x and y (X1,Y1)
take the last x and y (Xe/Ye)
fit a straight line to those two points for example by saying
(y-Y1) (Ye-Y1)
----- = ----
(x-X1) (Xe-X1)

That will give you the equation of the line through those two points.
Then try the other points in that equation. If they work, all the points are on the line through the first and last points.