How do you smart scissor a image on gimp and cut the backgro

[Ambrose]

If you want ALL of the white to be transparent. . .
1) Go to Layer<Transparency<Color to Alpha and, if white's not already the chosen color, change the color to white.
If you want a certain white region to be transparent. . .
1) Go to Layer<Transparency<Add Alpha Channel
2) Use the Color Select to select the particular region
3) Hit delete
4) Rinse and repeat for all applicable regions.