You must first of all have a valid passport which does not expire until at least 6 months after your arrival (you need this even if you are just visiting). You will also need to apply for a work permit. Usually you can only get this if you have already found work with a company registered in Brazil.

Your employer has to send an application to his or her local Ministry of Labour and Employment. This has to be approved, published and passed on to the Ministry of Foreign Affairs. If the Ministry approves it, then your Embassy can start the work of processing your visa. All this takes time, so you need to start early. There are several types of visa, and your employer will know which type you need, eg temporary or permanent.

You will also have to show a work contract, proof of qualifications and other documents. You can get full details here.