An easy solution would be to type an "x" into the cells of your choice (you
could also use Validation, select the cell(s) you want the user to be able to
select "x" or no "x" then go to Data -- Validation, under "Settings" tab,
choose "List" under the Allow: criterial; for the source, type "x,o" (without
the quotation marks), then press "OK." Validation allows the user to only
choose between those options that you listed through the use of a pull-down
menu.). To count the number of X's in a column use the formula:

=COUNTIF(A1:A4,"x")

Where A1:A4 is your range and your criteria "x." It will only tally a cell
if it contains x. You will probably have to change the range to suit your
needs.

Enjoy and I hope this helps, Jim