Hi Ozran,
in the Formula Editor for a column you can get built in references to many typical values of a variable by selecting "statistical" group of functions (i.e. col mean, col median, col max, col min and so on).
if you want to give a reference to a specific cell that is not the a regular parameter of a variable you need to slowly click twice in formula so it becomes a script and ad the number of the row in [].
for example, this column formula will divide each cell of the column "60 min" by the 25th cell of "90 min"
:Name("60 min") / :Name("90 min")[25]
Remember though that JMP is Not a Spreadsheet.