June, here's the easiest way I know:
1-Select a cell
2-Type =
3-Switch to another worksheet
4-Click a cell
5-Press Enter
That creates a link between the two. If you look at the cell where you
started, you'll see something like this: =Sheet2!C25. This says that
whatever value is in C25 on Sheet2 also appears here. Change the value in
the other cell, it changes here.
You can also create a link between two cells by typing the formula
(=Sheet2!C25 in our example) and pressing Enter, if you can remember the
syntax (which I never can, which is why I always do it by "pointing and
clicking," as in Steps 1-5 above).
Hope this helps. Post back with questions.