do I need to inform or call the embassy for schedule when to submit our visa application?

just go to embassy and submit your documents

Yes, no appointment is required by the embassy.

appearance in tha embassy
thanks for your reply on my first query,I understand that My nephew who is 20 years old need to appear in the embassy,Will the embassy set an appointment for his appearance after submission of our applications?or He can just come along with me during the submission of our application? again Thank you very much!

You may submit the documents on your nephew's behalf, and then the embassy will appiont a date to make a interview with your nephew. Or the embassy may inform your nephew to present at the Emabssy for the interview after the submission. Your nephew doesn't need to show at the embassy for the submission if it is not convenient for him.