How do I capitalize the values in a particular column? Do I use the function "UPPER" - if so, what is the complete formula?

There are two possibilities. =UPPER() will change the text to all upper case. =PROPER() will change the text to proper case.
If cell A2 has the word "john smith", use these formulas:
In B2: =UPPER(A2) to return JOHN SMITH
In C2: =PROPER(A2) to return John Smith

Copy the formula from B2 down to all of the rows where you have data in A.

You can then highlight these cells in column B, Edit - Copy, highlight A2, then Edit - PasteSpecial - Values - OK to overwrite the original values in A.

One note about =PROPER(). It works fairly well, but "mcdonald" changes to "Mcdonald" instead of the generally accepted "McDonald".