You can grade sizes visually, using your mouse.
To grade sizes visually:
On the Main menu, click Tools, then Sizes and Grading.
The Sizes and Grading pane is displayed in the Context view. Sizes are listed with the base size indicated.
The graded sizes and grade points are displayed in the 2D window. If the garment has no grading, only the base size appears.
In the 2D window, drag each grade point to where you want it to be.
The following image shows visual grading.