The only way you can fly for a career is to obtain a commercial pilot certificate. Best compared to a commercial drivers license the commercial gives you the privileges of flying for compensation or hire. This covers everything from flight instruction and crop dusting to piloting large airliners.

Before you can start training you need to hold at least a private pilot certificate. An instrument rating is also a good idea. At some point most also add a multi engine rating.

The commercial requires 250 (190 in Part 141) hours of total flight time. These are broken down in cross country hours, pilot in command time, etc. 

Training with a part 141 flight school the hour requirements are a little less. This way you can obtain the commercial at a minimum of 190 hours total time. It is also a requirement that you have completed the instrument rating, or currently enrolled in an instrument rating course.