How to erode an image using matlab and extract its boundary?

I need the matlab code to erode the given image using a 3x3 square structuring element and to display the eroded image. In structuring element, all the pixels are white and the central pixel is the representative point. Extract the boundary of the object by morphological operation and display it as a separate image. I'm not allowed to use any special Image Processing Toolbox commands other than imread, imshow, imagesc, and imwrite. Pls help me by posting the code asap.* Pls find the image below. Thank You.

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[Walter Roberson]

http://www.mathworks.com/matlabcentral/answers/29922-why-your-question-is-not-urgent-or-an-emergency