I am Bangladeshi. But now I am in Saudi Arabia...

You can travel to Poland with one of the following visas: 
1: Tourist visa.
2: Work visa 
3: Investor visa. 
4: reunion. 
5: visit visa
6: Student visa
After determining the type of visa that suits you, you should go to the  Embassy of Poland in the country where you reside and apply for the visa, you are accompanied by the following documents:
1) Copy of a valid passport for at least six months 
2) Two photographs with the same specifications of passport photo with white background for each
3) booking flight
4)Booked in a hotel 
5)Bank Statement 
6)Any other papers requested by the Embassy in addition to these papers by type of visa
After that you will be set up for an interview. In the light of this interview you will be given a visa to travel to Poland