Image Classi cation and Change Detection Training Data Creation Shapefile

[Alpesh]

Sir,

In Image Classication and Change Detection manual , 

in topic 4.3 Create training data: 

it is mentioned that "training data is derived from a set of shapeles, 1 shapele per class. These shapefiles were manually drawn using QGIS"

Sir,

what is the procedure  to obtain this shapefiles from QGIS?

Should I use clumps file  to obtain shapefiles from QGIS?

It is also mentioned that only 1 shapefile per class is generated for training. 

This creates some confusions.

Can you please suggest / give link of some tutorial kind of doc for this shapefile generation step?

Sir, Your guidance in this step will help a lot.