How to design a database and search with a filter for a bulletin board?

Question

Database design

Prompt good practices for database design and further search by filters.

Answer 1

normal form

Answer 2

Somehow I described the task too briefly)
https://www.w3schools.com/sql/default.asp - by filters, there are examples.
ruseller.com/lessons.php?id=1664 - how to design a database
How to design a database? - here the guys are sorting out the example
https://dbdesigner.net - a database designer, just in case.
php.net - for programming, useful