thanks @qglaude although i have already performed unsupervised classification and during that and before that i have learnt a lot about radar imageries but still i will learn more about its details. this presentation helped me a lot in learning the theories related to radar imageries. https://earth.esa.int/landtraining07/D1LA1-LeToan.pdf
However , i am not sure for the supervised part how the steps will be carried out in software. For instance, as Radar images are black and white so how can one distinguish training sets clearly and then make signatures from them? what tools should be used for making them and then performing the actual classification?