how to use ER-diarams for data analysis project

My project is about real Time data analysis website the website is so simple its just a normal user interface, user will register or log in and then should answer some questions and then the report will come out... I am trying to draw my ER diagram for this project but don't know either should I include the database real time data analysis or not? and how to mention the questions in the diagram? and if I do not include these the diagram will be so simple and small ...
+ if u suggests using other diagrams I will be so thankful

sorry for my bad English

thank you