using features extracted with SVM classifier

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I'm developing a paper. in this paper i had to extract (20 features for each region) from image after applying SLIC ( using regions instead of pixels) then i have to use SVM classifier i'm following this linkbut i couldn't found how to use my features extracted in the training phase to improve the training and test result. $could someone help me ?! I'm using visual studio c++ with opencv 3.4.0