This can also be done any time you like without formulas, if that is acceptable to your use case, using JMP's automatic filling capability. I add this even though Jim has answered your question, as an excuse to talk about this... many people don't know about the auto-fill features!
1. Create a new column.
2. Enter, in your case, 0.1 in the 1st row and 0.2 in the second row
3. Highlight both of these cells, then right-click, select Fill, and choose the option you want. You can continue the sequence to the end of the table or to a row of your choosing (JMP appends rows if this is needed, based on your input), or you can repeat the sequence to the end of the table or the row of your choice. If you include more than 2 values, JMP can tell the difference between arithmetic and geometric progressions, etc., and fill accordingly.
Cheers,
Brady