Alona,
While it may not be a requirement to attend an actual school, in my opinion you will benefit from attending one either online or in an actual classroom. The benefit is that they will assist you in getting ready for the state test which will be difficult to pass without proper preparation.
Hi, No school or classes needed for the general contractors license. If you want a plumbers or electricians license - yes, you need to pass a test and for that take classes.