Interesting grid problem to solve

I’ve got an assignment for an interactive grid and I have a feeling it’s pretty simple. I’m poking around at some solutions but I thought I’d post it here to see what you think.

It has to do with the floor plan of a big box store but the problem is simple: when you click on, say, row A, then click on column B, the box where they intersect lights up (or becomes visible).

I’m trying with if/else statements but no luck yet.