"I tried hitting the = key and then highlighting the cells but still cannot get it to sum."
That's because you haven't told 'it' what to do with the values in those cells.
Click on a cell to select it.
Press = to open the Formula Editor.
Type your formula into the Editor.
Click the green checkmark to confirm the formula and close the editor.
Example:
In the example, I want to show, in cell C2, the SUM of the numbers in cells B2 to B10.
Click on C2 to select it. Press = to open the formula editor.
In the editor, typed sum, then clicked SUM in the list of choices that was shown.
Which placed the SUM function, and a hint to what was needed next
I clicked the value token, then clicked cell B2 (showing behind fx) and dragged down to include the rest of the cells in column B.
The formula, in the editor, was now complete. It tells Numbers to
" SUM the values in cells B2 to B10"
Last step was to click on the green checkmark button to confirm the formula, close the editor, and show the result:
The full process of constructing a fairly simple formula may help when you are later working on a more complex formula.
For a group of these simpler versions, there's a shorter method.
When you select the cells you want to sum, a group of tokens appear at the bottom of the document window to provide the results of some common calculations:
If you drag one of those tokens onto the table,and drop it on a cell (such as C3), it inserts the formula that gave that result, displays the result in the cell, and shows the formula in the row where the token (and the other tokens) were previously shown.
Regards,
Barry
