how to select a block on image and save it to the objects with GDI+ c#?

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hi all.

How can I use GDI + tools in C# to select a block on the image and save it to the Object.
i can select many different shapes.
ex:
-Select the polygon format.
-select the rectangular.
block After selecting and Save the selected block into the layer (each block when the store will be named), Allow the layers palette click on the right to select a block, Allows you to select the block directly from the drawing Table layer (shown and click on the block was created) To fill a block is selected Delete a selected block,Zoom to easily select the block, Save (Save as proprietary format and still found time to open the image and the layer, allowing editing Layer), Export (Export to jpg, png, bmp), Fill Color (Based on the block is selected)
for example in link below:
http://thuenhanh.vn/B2_files/b2.png[^]

I found this problem a lot but unsolved .who can help me?
thank advance!