Help with using autosum in excel 2008 on mac mountain lion

Question

I am coming from pc world... love my new mac....and excel autosum is not working on my new macbook pro. I click autosum at the bottom
of a column with 8 numbers highlighted as I did on pc. And the correct sum shows in the cell where I want the total. But
when I click enter, the sum does not add the numbers. It just shows the sum formula. HELP! Been searching online all day for the answer!
38
8
1
6
44
7
5
16
=SUM(C3:C10)

Answer 1

The numbers I enter are showing up on the left side of the cell in the column rather than on the right side as they used to on the pc.
To set the alignment of text or numerals:
select the cells (could be one cell, a row, a column or a whole sheeti),
click Format in the menu bar and select cells,
click alignment on the top of the pane, then horizontal.
(You see that alignment is just one of the cell attributes you can set with this procedure)
I go to the tool bar, click autosum
You have to first select the cell where you want the autosum to be entered, then click autosum.
This way you can enter the sum of A3 thru A12 in cell P26 if that's what you want. The trick is to select P26 before autosum.
The autosum command will guess which set of cells to sum, usually the cells just above or to the left. But you can over ride that selection by selecting a different set of cells