Blend tool in GIMP

GIMP is the GNU Image Manipulation Program. It is a freely distributed piece of software.
It is quite similar to PhotoShop. It can be downloaded from:
http://www.gimp.org/

To use blend tool in GIMP,
1)  Click File at the top menu, then enter width: 400, Height: 300
2)  Click Edit at the top menu, click fill with pattern
3) Click blend tool in the toolbox or right click mouse, choose Tools->Paint tools->Blend
4) Select default in gradient, right click mouse and drag it from left to right in the rectangle at the stage.
The result picture is as follows: