Air ticket in brazil

After so many days I am back again. I live in indaiatuba of Sao Paulo. I want to go to mato grosso for job purpose. How to buy air ticket? How it would be cost? What documents I need for this traveling?

There are many travel agencies. You can buy direct from airlines and travel sites online.
The price goes up (notice I did not say down) every day. Many routes and flights have been reduced, and means when one seat is purchased, the fare for any remaining seats increases.
So no way to know the price without a lot of information.
Just go online for an airline or Expedia type website for an idea of availability and price on the days you want to fly.
Be ready for a price shock. Some fares pre COVID are now 3 or 4 times more.
To travel you need a passport & visa, or passport and RNM, or BR ID.
Nothing special for domestic travel.

https://www.submarinoviagens.com.br/https://www.decolar.com/passagens-aereas/https://www.kayak.com.br/https://www.cvc.com.br/