You can test your classifier even with single verbatim and see if the classification is correct. This is good for getting a first feeling about the classifier accuracy.
To do this select "Single Text Processing" in the Voc Classify main menu.
In the tab "Classification" (the tab is opened by default) select the classifier you want to test.
Next, type the verbatim you want to classify and click on "Apply":
As you can see in the picture above, the text has been classified correctly as "Negative".
You can also use Single Text Processing to train a single verbatim, selecting the "Training" tab. Then, write in "Text" the verbatim you want to train, select the right category (Positive, Negative or Neutral in this case) and click on "Apply".
If the process is correct, you get a message as "Classifier was successfully trained with TEXT" and the single training case will be added to the other trainings of your classifier.