Hi, i want to ask can i classify based on pixel in snap? if possible how? please tell me, because i was saw in journal but i didnt find it. Or i can do it in arcgis or anything, please answer me 
Thankyou.
Sure, you can do this. You can use for example classification methods like spectral unmixing, or supervised or unsupervised classification or Random Forest classification. You can also use IdePix (needs to be installed as plugin) to classify the pixels. And you can use Band Maths to investigate pixel values.
Explaining all this would need to much time.
I would suggest that you a look in our tutorial section where SNAP is explained in general our you have a look on YouTube where video tutorials exist for this topic (search: snap classification - YouTube).