how to Test Data schema in query editor in adobe Campaign Classic.please help me on this part

Can you be more specific? provide more context.

Do you mean; once you created your schema and deployed it, you want to test it by using the generic query editor? alternativaly, you may use the same steps below to configure your query activity in the workflow to fetch data from your schema.

1. Go to Tools >> Generic query Editor
2. 

    

3. Type the name of your schema and click next.
4. Select the columns you want to display (data extract) then next
5. Apply sorting based on a column (optional), Next
6. Configure your condition by chosing the criteria.

Here are some docs for support

• https://experienceleague.adobe.com/docs/campaign-classic/using/automating-with-workflows/targeting-activities/query.html?lang=en
• https://experienceleague.adobe.com/docs/campaign-classic/using/getting-started/creating-queries/steps-to-create-a-query.html?lang=en