Add values on same column

[#1]

How can I add the N rows and store the sum on the next column?

[#2 · Accepted solution]

Create new column with a formula

Col Sum(:N Rows)

You can also right click on N Rows and use interactive formula builder

which will create same formula

[#3]

Please see Jarmo's     @jthi  response for the solution.  I also suggest that you take the time to read through the Discovering JMP and Using JMP documents to add to your efficiency in using JMP.  One of the JMP features that is covered is the Formula Editor, which interactively presents all most all of the functions that can be used in the calculation of new formula columns.