Extension development

Is there any one who help me what the architecture of an extension should looks like in PostgreSQL database.

Regards,
____________________________________
Yonathan Misgan
Assistant Lecturer, @ Debre Tabor University
Faculty of Technology
Department of Computer Science
Studying MSc in Computer Science (in Data and Web Engineering)
@ Addis Ababa University
E-mail: yonamis@dtu.edu.et<mailto:yonamis@dtu.edu.et>
yonathanmisgan.4@gmail.com<mailto:yonathanmisgan.4@gmail.com>
Tel: (+251)-911180185 (mob)