I assume that you know how to make a JMP data table and enter the data. I will call the three independent variables X1-X3 and the dependent variable Y.
- Select Analyze > Fit Model.
- Select column Y and click Y.
- Select columns X1 through X3 and click Add.
- Click Run.
- Click the red triangle at the top left and select Save Columns > Prediction Formula.
Now you will have a new column, Pred Y in the data table. You can use it like any variable at this point.