what is that small square white rock thing call? i think it can keep good bacteria?

[Nuttawet]

what is seachem, what does it looks like and what does it do?

 

[Essjay]

Seachem is not a thing. Seachem is a company which makes a lot of different aquarium products.

 

[GaryE]

The best strategy is once you have a name for something, google it.

Seachem is a large, important company in the US and Canada - probably in Europe too. You probably have access to just as good products from their Asian competitors.

 

[Essjay]

This is Seachem

Seachem Laboratories

www.seachem.com

 

[ShrimplyKay]

My God, you all have too much patience for this nonsense.. do a bit of research! Literally just type anything into any search bar, and you'll get an answer. We are not your personal dictionary/inquiries...
Sorry to be that guy but it does take a bit of ambition to be a good aquarist, and you are lacking my friend, go on a little research adventure and learn some things about the hobby.
Get those poor bettas out of that tiny box, and learn something about filtration. The ceramic biomedia rings you keep asking about, those go inside a filter.
The bacteria you're asking about, is formed when you let the empty tank sit and balance itself out, some times with chemicals some times not, that is called the Nitrogen Cycle.
If you don't know these terms, search the internet for them, it will do you some good to teach yourself something
I'm sorry if I am being a bit rude but what you are doing is also a bit rude.. take some initiative and do a little research. Browse the web, read a book or an article. You got this, ok? Anyone can learn this stuff, you just have to put in a little effort