A 4 year bachelors degree or equivalent is required. Exceptions are made for people with a lot of experience or if you are an extraordinary person (e.g. You have no degree, but you are Euler).
If you google, The basics of the H1-B process is well discussed and explained by lawyers on multiple websites. Since there are a lot of immigrants who have gone through the H1-B process, there are a lot of forums where lots of nuances have been discussed by people on all types of visas, people applying for green cards, etc.