Hi

To obtain a work visa in Poland, you must obtain a work contract, and then go to the Embassy of Poland in the country where you reside, and apply for a visa,
As for the visa online, it can be obtained through the following link:
visa
The application shall be 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) Copy of the contract of employment or letter of employment